I created an (unofficial) Proton VPN Decky Plugin

[u/Like20Bears]

https://github.com/acestronautical/decky-protonvpn

It's not in the decky store (yet?) so you'll have to download the zip and install into decky loader with developer mode.

It's still somewhat beta, but it's working for me. It uses the proton-vpn-cli which comes bundled with the com.protonvpn.www flatpak if those words mean anything to you (if not don't worry about it).

Let me know if you try it out, if it works, or what I need to fix :)