I support this, enough so that I have joined and posted in these forums for the first time after having a Proton account for around 10 years.
I want to use CachyOS, but I know full well that I don't have the skills to verify trust on AUR or unofficial FlatPaks. Just knowing that a FlatPak is verified as distributed by Proton officially would be enough.
As W11's issues with privacy and security become more widely understood I think more and more people are going to end up landing in my situation. I also think that anything that has the potential to lead to "Proton or Linux" situations, will probably fall in favour of Linux more often than Proton.
(Even better than just an official FlatPak would be to also do official packages through apt, dnf and pacman, but that's probably just being greedy :) )

Makes more sense to have only 1 official format of distribution in the form of Flatpak. Interested parties can create .rpm, .deb, Snap or other packages as needed.

I would also love to have the option to install a snap version of the desktop app.

Official VERIFIED Flatpaks should happen ASAP for Proton Pass and Proton Authenticator.

The average user who has just switched to a Linux desktop is going to rely entirely on his distribution's app centre to find and install software, not start manually updating DEB or RPM packages.

These products are NOT going to be able to compete for his attention as standalone apps unless they are one-click installs and update automatically. Even as a more experienced user, I also want those conveniences. Flatpak provides both of those things on a wide variety of distributions.

Right now the UNVERIFIED warnings for Proton Pass on Flathub instill avoidance rather than confidence in something as sensitive as a password manager.

Almost 2 years yet no Flatpaks. Disappointed

Devs? Any updates regarding this?

The flatpaks exist already, Proton needs to make them official.

Adding another voice in favor of this. There is a wide ecosystem of Linux distributions that are not downstream of Redhat or Debian, and an official flatpak release is an easy way of providing Proton apps to a large number of them.

Definitely favour Flatpak support!

Yeah, I agree. I even fell for it. When I asked for support they told me that official packeges are those only from their websiate (.deb and .rpm).

Someone published Proton Pass to Flathub:

https://flathub.org/apps/me.proton.Pass
https://github.com/flathub/me.proton.Pass

Proton should definitely take control of these

This idea might be relevant too, it proposes all Proton app be made available as Flatpaks:

https://protonmail.uservoice.com/forums/945460-general-ideas/suggestions/46955335-official-flatpak-support-on-linux

As a Steam Deck user, this is really needed