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
Yeah, Mozilla thought about bringing official support but discontinued is afaik.
That’s extremely unfortunate. I can’t see how it would be all that difficult to implement (says someone who absolutely would be lost looking at Firefox’s source code lol)