Not really that worried but rather curious about your opinions. Use what suits your demands best.
But for starters:
Electron is a framework based on Chromium used to develop desktop apps. Examples of apps that are built on Electron are Discord, Element Desktop, MS Teams, Slack, GitHub Desktop, Atom, VS Code and counting
Tbh, I don't use that many plugins either. Besides U-Block I got:
Plasma Integration so I can search bookmarks via KRunner;
Dark Reader because I don't like bright colours;
Gesturify because I love mouse gestures;
Some translator (I've forgotten their name)
Simple Tab Groups to stay organized;
Progressive Web Apps for Firefox (but I'm currently testing which plugin works best)
Honorable mention: Tab Discard, which I used to have but Firefox kinda has something similar now (or at least Floorp has, they also got their own Workspaces so I also don't need STG any more)