Manifest v2 extensions are still very much working in Vivaldi. I’m on version “7.6.3797.63 (Stable channel) stable (64-bit)” which is the version currently available for download directly from vivaldi.com.

I still want to try Floorp and Zen Browser before I settle on a for-now browser though. Eventually I’d like to be on something Servo-based, but Gecko would be preferable for now if I can find one that works for me.