Vivaldi web browser is now available on Flathub! https://www.omgubuntu.co.uk/2023/11/vivaldi-web-browser-flathub
@omgubuntu Ok Joey, since you are one of my favourites I will answer any questions you have on this. Just ask!
I will clarify something though. Yes, I put up the flatpak and yes I am a Vivaldi employee but for the time being it is not an official Vivaldi flatpak (hence the lack of tick). I can make it official but I have chosen not to while I test the waters.
It is up because of overhelming demand from users (unlike snap) and I wanted to get something out since all the others browsers are there (albeit most of them not official either) and Vivaldi was notably missing but I do have some concerns about Chromium browsers running under flatpak. I will accept that my fears might be completely unwarranted. I should get someone more technically competent to check before we make this 100% official.
@omgubuntu Just to expand on why it is not official.
The Chromium sandbox is actually very good and it is fully interprocess. My understanding is that Flatpak's sandboxing is typically to separate an app from other apps and/or from parts of the OS. The difference is that in Chromium if you load Facebook in one tab it cannot get access to the process that runs Youtube in your other tab.
But the Chromium sandbox needs greater integration with the OS and the attempts by flatpak to handle sandboxing clashes. Thus all the Chromium browsers and Electron apps use a trick (Zypak) which fakes part of the chromium sandbox.
In short, Flatpak doesn't allow important parts of the Chromium sandbox to work as intended by the Chromium team, when running under Flatpak. So it appears to me that you end up with a key part replaced with something potentially weaker and certainly less well understood and tested. Zypak looks like is maintained by a small team, primarily a single person (that is not to knock them, it is impressive and they clearly know a lot more than me!). But for comparison those responsible for the Chromium sandbox are a bigger and more established team.
@omgubuntu I do not currently feel totally confident that you aren't actually getting less security trying to run specifically a Chromium based app in Flatpak (for other apps there are only benefits).
I also strongly suspect this is probably why you are not finding a single official flatpak by any Chromium based browser (last I checked). Either they decided it is less secure or they too suspect it might be and do not want to take a risk.
Until I understand it better or have our devs review Zypak, I am leaving it unofficial and would encourage the use of an official deb/rpm app (or even one of the many fine distro repacks using traditional packaging) over the Flatpak.
But again… I could be wrong!