Yeah, it’s an app on the play store - I’m not sure if it’s just android or available for iphones as well, but it’s called Flaming Durtles.
It works offline, which is why I started using it, but it also incorporates a lot of (optional) functions that work similar to popular userscripts.
Okay, I just checked the forum thread for it on here, and it is only for Android. That thread is very active, so if you’re interested feel free to check it out and engage. 