Mozilla VPN missed a real trick by being an additional client and not (also) integrating it into the browser/container natively.

Was a real chance to do something better rather than just doing the minimum (rebrand an existing VPN client app) and potentially pulling in a new customer base.

Not exactly the same, but there is FoxyProxy extension which allows to use different proxies based on URI (domain). So you can point your uris to go to outside world via different proxies (say `ssh -D ...` to vps or your vpn gateway or ..)

Technically as it's possible to use multiple profiles you may even be able to configure different sets for the same URLs.