I think the best UI would just be a page change foot pedal. Not particularly difficult to implement and very reliable.

That's what many big-name classical pianists use, a pedal hooked to an iPad.

Why iPad though? I’ve seen a specialized electronic music sheet (seemingly based on e-ink) in some videos, I guess pages are flipped using a pedal since I didn’t notice any visible interaction with it to do so, e.g. https://youtu.be/oB-gF2Ncphg

I think the question quickly becomes why not an iPad. They're easy and pretty cheap to get hold of, have good screens, lots of people can easily write new software for them and they're also a tablet. Many people may already have one and so using hardware they already have is much cheaper than buying new special hardware.

Also, eink screens are nice to look at but so expensive for non-kindle sizes.

I've played so much live music with an IPad, but after the 4-5th time having it freeze up mid live performance I gave up on the dream. It's just not 100% reliable, and nothing like standing there like an idiot desperately trying to swipe to the next page to make your realize how great paper is

that really sounds like the software you were using not the ipad itself. most people essentially NEVER have their ipads freeze.

chucking the ipad because of that is like chucking the baby out with the bathwater because the bathwater got cold. The baby still has value. you just replace the water.

cool video. looks like the remarkable, actually two of them. now i need to buy TWO