The Simple DirectMedia Library that is widely-used by many cross-platform games and part of the Steam Runtime now has better support for handling more mouse button events under Wayland.
Last week was a bug report over supporting more mouse buttons than five. While some mice end up binding their extra mouse buttons to keyboard keys, some mice such as when configured via Libratbag+Piper can map them to higher key press input event codes. Theoretically, allowing up to 48 key press input events in total.
Huh, I assumed that scrollwheel up/down counted as button presses. Guess not.