In addition to this idea of control Extensions just need simple security stuff & rules:
Rule if user wants extension to be able opening new tabs(always, ask, never)
Actually today I had very important website session, and suddenly extension opened their promoting tab 😕
Rule or white\blacklist for background(or full) internet usage for extensions!
For example some Web2HTML doesn't need any internet access. Also some ad-blocker doesn't need any access, except blocklist updates.
Rule for Requests access(read-only, read-write, no-access)
So most of extensions won't be able to read your site-requests(might be personal data!)
Rule click-to-run for every website(always, white\blacklist, never)
Same as quarantined domains, but controlled by user.
Rule for WebExtensions runtime.sendMessage()
To protect extensions from unwanted communication
Complete activity log for every single extension
Current about:debugging shows only the console - what extension wants to show, not their real actions.