Sounds like you already have a pretty good plan in place.

One extension you might consider is libredirect. Instead of manually copying a random youtube link, pasting into the url bar, and changing youtube to yewtu.be, you can just click the link and let libredirect do it for you. If the front-end gets 429'd, you just click the "switch instance" button until you find one that's unblocked.

You might also like Simple Tab Groups, if you ever have trouble compartmentalizing a million open tabs. Might be disruptive to your workflow though.

Another Only Up clone?

Either Garuda or Mabox. The next time I do an install, I might just mix and match repos and hope I don't break anything.

Manjaro was my first distro, and I still have a soft spot for it despite its flaws, but I tend to think Garuda now does a better job filling the Manjaro niche in just about every way.