Does anyone know of mods that have been made for bitsy? I'm curious if there's a standard way to implement them. All I could think of is rewriting the `_update` method.

You might want to check the bitsy hack repository! It covers how to implement and has links to a lot of the commonly used hack supports and engines based on bitsy, though as far as I know there are no mods that can be used directly from Bitsy itself (I hope if I'm wrong someone else will chime in!)

https://github.com/seleb/bitsy-hacks/blob/main/README.md

yup the hack repository has the most standard conventions for modding bitsy 

(of course you can also just crack open the html file and edit it however you like too)

if you’re interested in a GUI solution there is also borksy

https://ayolland.itch.io/borksy