Suggestion Device (i.e. iPad) for having piano sheet music?

The particular iPad model doesn't matter as much, but depending on your eyesight you may want to consider a 13" iPad over the 11" iPad.

I recently switched from using PiaScore to using forScore to manage sheet music. ForScore allows you to import and organize on your Mac directly and wirelessly sync to iPad, which makes importing a breeze if you have scores on your computer (although you can also directly import on the iPad or use the camera to scan and import). You can use electronic page turners as well, some of the models you can find here (I have the PageFlip).

I have an ipad pro.  I scan using the notes app already on the ipad (in scan a document mode) then I can have it open in my music app.  I use Forscore as it allows my digitallly purchased and my scanned music to work in the same place.  And the best part:  it has facial recognition for page turns so you can set it up to register a smile or a head turn etc.   I find it much easier to use than a foot pedal especially when accompanying singers that need me to use both feet already for soft and damper pedals.  

I have my digital everything on a few devices. I have an ipad pro 6th gen, a 2 in one laptop as well as a desktop and another laptop. I keep my stuff on the laptops and desktop but for versatility I also have all my stuff on what's call a Network Attached Storage device (NAS). The contents of that server can be accessed anywhere any time. I use one from a company called Asustor which is a sub of Asus. I usually use Asus motherboards when I rebuild my desktop. I would recommend the NAS for various reasons including backing up data. Along with that consider using a VPN for personal protection. The NAS by Asustor isn't too expensive. The hard drives will add up but this should be a one time purchase. I hope that helps since it's a bit more than expected but I am a retired programmer. 

When I bought an iPad 6 years ago it was strictly for piano scores and was the first Apple I'd owned since the 1980s.
I chose it over the less expensive Windows or Android tablets because the screen's aspect ratio was a better fit to music pages.

forScore is a beautifully designed app (Apple only).  It's obvious that the programmers eat their own dogfood (i.e., actually use the app) and that it's a labor of love.

I download PDFs onto my Windows laptop from IMSLP or use a flatbed Canon scanner to scan in music I have physically, then transfer from the laptop to forScore on the iPad.  (I have an app on the iPad called "FE File Explorer" that connects to my laptop.)

forScore also has a "stamps" pad of numbers that I use to put fingering on my scores.  Much neater than scrawling with a pencil or stylus.  And, being an ancient Luddite, I sometimes then transfer the so-fingered scores back to the laptop as PDFs and print them for use at the piano.  (Old age...)
 

I use a 13” iPad with the ForScore app and a FireFly pedal (by PageFlip) for (page turning).   Takes some getting used to but definitely worth it!  You can send downloaded music directly to ForScore, which allows you to categorize music however you’d like.  I categorize by instrument (piano, violin, and whatever other instrumentalist playing with).   I subscribe to IMSLP and download those scores directly into ForScore.  There may be newer pedals than FireFly out there since I bought mine several years ago.  Anything smaller than 13” is too small for complex music.  ForScore had SO many more functions that I do not use but would love to learn, e.g. multiple overlays of  the same score for making notes from various sessions.  Good luck in your search!

If you mostly play piano at home I find it best to first focus on a PC (or Mac, if that's your thing) type based solution. I use the Newzik app (which works on an iPad as well as PC/Mac/Smartphone). I mostly use Newzik in a browser (chrome) running on my PC next to my piano and a 27" monitor on the music stand. Then I can see 2-pages at the same time - nice and big. (Even the biggest iPad can only reasonably show 1 page at a time). All your scores are stored in the Newzik cloud so when you go remote on an iPad or need a quick check of something on your SmartPhone, all your music is there (after a synch.). Some editing tasks I prefer to do with a mouse on a PC, others I use my iPad and the "apple pencil" type device. It's all the same back-end data so they both work and I keep my iPad close when practicing for "easier to draw with a pencil than use a mouse" type score updates. If you take lessons, Newzik allows stuff like creating a "project" you can share with others like your teacher and they can directly add annotations on a "layer" of your score. Especially helpful if you take zoom lessons. The music you play from is the same as all the other apps: PDFs of music you scan with your phone or PC/Mac-scanner and/or PDFs you buy from online providers. Hands-free page turns on any device are most often usually done with a Bluetooth pedal that links to your PC/Mac or iPad. My current favorite is made by Donner. Though some apps (maybe even Newzik for all I know now) allow you to squint your face in certain ways/wink/etc. to turn pages. The bluetooth pedal becomes second nature like any skill so I prefer that.

I find Android devices much better, more flexible, less restricted then Apple devices and the software I use, MobileSheets (https://www.zubersoft.com/mobilesheets/) is extremely good and has a lot of features that make it easy to import, share, use, backup etc. scores, combine them with audio, use a metronome, use a Bluetooth pedal to turn pages, even have two players sync their tablets while reading e.g. the Primo and Secondo scores.

The device is a Samsung Galaxy note pro with 14" screen and a pen that lets me add fingerings, markings etc to the scores.

If you rather prefer Apple, the MobileSheets software is also available for iOS.

Hi Roger.. I use the mouth/nose.  Initially, I was using the eye gesture.. but pages were turning involuntarily due to looking "the wrong way"..so I changed to using my mouth/nose.. On a comical note, I if I have a cold or sinus issues (or anything that affects my mouth/nose area used for turning pages.. sniffling or twitching your nose ), pages will turn quite rapidly!!!!

I have a Huawei MatebookE hybrid, i.e. a PC that can become a tablet.  I use the Mobilesheets app which is easy to use (can import any pdf or jpeg sheet music, file it,, allow notations on it, allow you to attach recordings so you can play along etc. ).

ForScore has a nice feature that displays scores across two iPads. I have a first-generation iPad Pro that is partially damaged but works fine as that second device. It doesn't seem like ForScore requires the latest hardware, so you might consider getting older device(s).