Yep, also they don’t integrate Pocket in the browser, they just have a built-in email client, note-taking software, RSS reader, calendar bloat. Also, Vivaldi is based on chromium (as such subsribed to all Google’s bullshit), and uses Chrome extension store.
Honestly, OP, just stick to Librewolf, it’s privacy-respecting and actually open-source, pocket’s disabled, UBo’s preinstalled.