Thanks for pointing this out. I had no idea it existed. The other options in the comments just didn't quite work the way I would like.

- The main topic requires me to pull python dependencies, build, run manually on Mac - All others can't reassign the button below the scroll wheel on the MX Master 3/4

I switched to the offline version right after Logitech forcefully and without my permission downloaded and installed bunch of crap software on my Mac. I was furious that a stupid mouse driver app has the right to install a random crapware. I’m still fuming about it when I remember it.