I find this extension very useful, but still somewhat lacking in my particular use case.

I share web site passwords among several browsers, and don't feel comfortable giving each of them (or even: any of them) full access to all the vaults. A compromise in one browser or any of its extensions shouldn't risk to expose high value assets like credit cards or infrastructure level passwords. Yet it doesn't seem possible to restrict access (I have a Proton Unlimited subscription) to one particular vault.

I worked around this by creating an additional free account solely to manage these less critical passwords: one can't compromise what's not even there. I'm not even sure whether this procedure is acceptable use, I didn't find anything against it but then I didn't look very hard.

I also noticed that access tokens have been introduced recently, so maybe features like this are on the roadmap somewhere.