The Supernote is running a version of Android that let’s you sideload stuff, but I haven’t messed with it too much. There are also boox devices that are Android based and the inkpalm from Xiaomi.
For the most part though, I think the android versions they use are generally very old.
Meh, Supernote could shutdown tomorrow or upgrade to Android 16 and neither would change anything about how I use it. They also made the internals of this generation replaceable.