You can if you code it. It’s a simple user script that associates a note with a name and puts it in browser storage and then appends it to their name. I was making it but I stopped because I had work to do and had no time to play with browser add-ons.
I can code it easily in a few hours but I’m working my ass off right now to get some company stuff done. If you can spare a few dozen bucks I can save a few hours this week for it. You can also try and make it yourself. I’ve made similar plugins and posted them on !plugins@sh.itjust.works. (i am @God there). If you check out my code and that of others, I’m sure you’ll have a lot of reference for it.
If no one else has made it, I already started the add-on but I’ve been too busy to finish it. If no one else does, I will probably build it for myself and publish it there in a few weeks when my work gives me some time for hobby coding.
edit: if you do take a look
this is very simple, here, check out the mutation observer, the username grabber, the function that appends a tag to the username, it’s already there
https://sh.itjust.works/post/89693
and to do the custom tags, you’ll need to check out how to use localStorage: https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage
that’s about it, you can trigger opening the tag modification with a simple window prompt https://developer.mozilla.org/en-US/docs/Web/API/Window/prompt
and you’d append a button that opens the prompt when you tap on a username’s tag or icon that indicates that there’s none. the button would open the prompt through an event listener: https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener
modifying colors is the simplest part with inline css: https://www.freecodecamp.org/news/inline-style-in-html/, it can also be stored in the localStorage.