While I figure out if it makes sense for me to get a second sheet-music-only tablet, I decided to make my existing tablet "less permanent."
I had a tablet holder with spring-mounted clamps that secure the tablet in place. But it's almost impossible to remove the tablet from the clamp without worrying about dropping it, or dropping it on the piano. So I removed the clamps, and instead printed a dock that can sit at the top of the lid, provide 24/7 drop-in charging with a hidden USB cable, and allow the tablet to be removed and dropped back in nearly effortlessly.
I started with some basic geometric shapes to see if I could easily "capture" my USB charging cable in the right orientation:

The final print files:

My 3D printer is a bit too small to print a dock the full width of the tablet, so I printed it in two halves and epoxied them together:

Added a bit of felt to protect the parts of the piano it would sit against:

Installed in its little nook:

View from above - the cable routs towards the front of the piano and drops out of sight in the gap between the plate and the front board:

Tablet inserted into the dock:

And importantly, it's nearly invisible from the seat:

So far so good! The tablet is stable, I can rest my palm against it while annotating with the stylus, no buzzes or vibration while playing, and I can now just pull the tablet up gently and it lifts out of the USB plug, and when I'm back I just drop it straight down and it clicks into place.