Does anyone have information on if the Safari Stylish Addon does the same shady things? It's available in the official App Store and was approved by Apple it seems.
Edit: I should note that it collects analytics, but it can be turned off in the preferences. I don't remember if it's on by default, but I suspect it is.
Tampermonkey is here BTW: https://tampermonkey.net/?browser=safari
I really love that one, it does a great job in Safari. Unfortunately, there is no Safari App Extension yet. Since I'm running Safari Preview and Safari 12 does not accept extensions from unknown sources anymore I'm out for now.