I've used everything from "selfie" clickers to A/V 5-way remotes to single foot pedal to 4 button foot pedal. Usually the problem is to get some reasonable button values which work with the applications that you care about. Yes, you can remap the buttons at the system level with /system/usr/keylayout/Vendor_1234_Product_5678.kl (Bluetooth devices have VID/PID equivalents to USB). Still, that makes things more complicated for using various devices.
You can also add/change key assignments at the application level too, especially if it's open source.
Onyx/Boox makes a TV-like remote that's applicable to their models, but most of the button choices wouldn't suit other users. It uses a lot of F1-F12 keyboard keys.
I've actually designed and ordered some custom circuit boards to put in a generic clicker case. This is the one on the right with four buttons. I'm thinking forward, back, menu/refresh, sleep?
There's a thread here:
https://www.mobileread.com/forums/sh...d.php?t=341684