Yes, Tampermonkey is still a thing. As I'm sure you've noticed, MTurk has changed quite a bit in the last two years, and so have the scripts that we use. Honestly, if you're just starting out again, I would probably just go with something like MTurk Suite. It's a browser extension that contains a handful of tools for MTurk, like HIT Finder (which is like HIT Scraper but much better), HIT Catcher for running pandas, HIT Tracker for maintaining a database of your completed HITs and tracking your earnings, and there are some other things included with it. I would say start with that, then you can start looking into other things based on your needs.
Also, you'll see a lot about TurkerView. That's kinda like a replacement for Turkopticon that I think most people are using these days. Both are included with MTurk Suite, though.