Got here from @buyfromeu after switching browsers (from firefox to vivaldi) and making Qwant my search engine of choice.
Honestly I love @Vivaldi and I wish I knew of it beforehand. It has all sorts of nice features including this mastadon integration.
I鈥檓 sorry to break it to you, but Vivaldi is built on the Chromium engine, which is the same engine used by Google Chrome. As a project it depends on Google which is not an EU company.
If you have to chose a fork from either Google or Mozilla, I鈥檇 say Mozilla is the least evil. I would suggest Mullvad browser as a better EU substitute. With either librewolf or Icecat as runners up (although not sure if EU based)
There is also ladybird which is a entirely new engine and not based on either Google or Mozilla鈥檚 work. It is open source and non profit but I鈥檓 not sure if they are based in the EU.
Enjoy Mastodon!
As others have said, Vivaldi is based on chromium and bibs you to google. That can鈥檛 be better than Firefox.
Yes, its nice, if you want to stay on firefox-based browser, you could try Floorp, but it is japanes, not EU