I use it primarily with Vivaldi - works great for me. (And I love that Vivaldi encrypts my synced feeds - so the data is mine even if I’m syncing it through them for the time being.)
I’m just waiting for the extension to get approved through the Chrome Web Store. I expect that this will be something of an ordeal - getting my extension through Firefox’s approval system has had quite a few hang-ups that could take me a month to resolve. But thanks for your vote of confidence, Brad!