Well, calling it an eReader is a bit of a stretch. More like a "dual screen, large format, e-Ink, sheet music display device". I've been wanting such a thing to automate page-turning for piano for a long time, but the price of this device is a bit on the astronomical side. Sheet music is somewhere around 9"x12" in size, and there just aren't simple, lightweight displays to handle this that are readily available.
This device looks almost perfect ... except for the price! Hopefully you can get a foot pedal for page turning. I'm not sure it's actually made it to the US market yet either.
https://youtu.be/ZXNQ310cIsM
https://www.gvido.tokyo/