You can download configuration files (wireguard preferably) from your protonvpn account in a web browser.

Open the network manager (idk what steam mode uses, this should work in desktop mode) and add a wireguard connection.

Add the private key, add the peer and its public key, add the dns. Save.

When you need it, simply connect to it like a regular network, in addition to your wifi of course.

This has served me well on Fedora Atomic workstation with KDE for years :)

ProtonVPN supports the OpenVPN client , so you can import your proton VPN settings in to that, no need for the official proton VPN GUI client.

However you do lose some of the more advanced features of proton VPN.

Hello, you can install a Decky extension to use OpenVPN. And use protonVPN OpenVPN config in desktop mode. I use it on my deck work fine in both mode once configured

Unfortunately Proton has very limited support for Linux.

If you installed via the Discover Store, you probably installed the old, unofficial Flatpak version that hasn't been updated in over a year.

Proton actually JUST released a new "stable" Linux client. Here is the link with instructions to install via the Arch repository: https://protonvpn.com/support/official-linux-client-arch/

Unfortunately you DO have to use the terminal to install it.

Alternatively you can do what I did and buy a gl.inet router which comes with OpenWRT pre-installed and it's an absolute breeze to get a VPN managing traffic on your router directly across your entire network and not having to fuck with that shitty Linux client ever again.

So steam deck is arch based. I just installed arch on my desktop with gnome. I couldn’t get proton vpn to work at all until I installed network-manager-applet. Then it worked fine. (It wouldn’t connect). I had to do a ton of googling before I found that fix, I think a lot of people give up on proton vpn before they find that solution/dependency. It sounds like other packages can provide what proton-vpn is looking for, but I think network-manager-applet gets installed often enough as a dependency where it just works for some people, while for others getting proton to work is a chore. (I’m pretty sure it’s not installed on a fresh install with gnome - making getting proton to work on a bare bones install challenging). I dunno if that or another package is already there on the steam deck - but worth checking that line of troubleshooting out.

Now, if it’s not there - I don’t know the full dangers of installing that package on the steam deck, maybe someone smarter can comment on that. It should be noted that I installed network manager with pacman and proton vpn from the AUR. I don’t know how the flatpak would behave - but it didn’t work either without network manager installed.

Good luck!

Proton VPN messed up wifi in gaming mode for me, it basically auto starts and fails to connect on boot, and it just stays connected to proton so wifi doesn't work.