Just found my Vivaldi update contained a little more than just bugfixes… it now has Proton VPN built in.
It’s actually part of the browser, not an extension, so I’m in two minds whether I like that… or not.
You need either a Vivaldi account or a Proton account, so it’s not completely anonymous, but it’s a start.
The free-tier of Proton VPN also appears to be bandwidth limited and your exit point is randomised, so… yeah, it’s ok…
AFAIK that was a telemetry issue that was fixed (but very poorly addressed.) last year. Then someone posted about it recently…