I'm attempting to build a monk that relies heavily on quarterstaff attacks. Does anybody know any homebrew subclasses that are based around or support quarterstaffs?

All monks can use quarterstaffs effectively, Kensei can offer even more bonuses / features for fighting with quarterstaffs.

Not a subclass and they were designed for rogues, but here's a line of magical quarterstaves that might be useful:

Acrobat's Pole

Tumbler's Pole

Aerialist's Pole

I also have a Staff Fighting feat, but the main benefit of the bonus action attack is already covered through monk's Martial Arts.