I was able to install one in a chroot, but I'm not sure if it makes sense for you, since you have to set up all this:
https://www.mobileread.com/forums/sh...4&postcount=53
Then:
apk add xournalpp
apk add adwaita-icon-theme
You have to enable touch drawing from the touchscreen section in preferences, or else touch will just pan the screen instead of drawing.
Hope you have a big powerful device, because on the tiny Clara, while usable, is not the most efficient way to enter long HANDWRITTEN notes I would say.