Submit Linux package updates in official distro repos
Proton VPN is open source and uses well-known and established components of the NetworkManager stack. Due to these two things, there is virtually nothing standing in the way of the Proton VPN team from building and submitting packages officially to Linux distributions like Fedora, Debian, Ubuntu, EPEL, etc. Proton VPN is further enhanced by packaging upstream by increasing the availability of Proton VPN software packages in the global software package mirroring network (deterring censorship) and benefiting from improved transparency and openness by building packages through distribution-supported build systems, which are often reproducible.
The policies of most distros are friendly to this since the Proton VPN Linux pieces use Open Source licenses. A community-supported Fedora Proton packaging SIG already exists.
Implementing this is both a matter of technical expertise but also being able to navigate and collaborate with other communities. Proton engineers would submit package updates directly to Linux build systems and benefit from being stakeholders in the distribution end of software production. This also gets Proton engineers closer to user feedback and bug reports.
(Not to be biased, but I get copied on bug reports for Proton VPN bugs in Fedora and I am not always sure how to best route that feedback from distro users back to upstream developers.)
One idea for the Proton-hosted repos is that they could still be provided, but for beta or experimental users. This way, Proton still maintains a mechanism for shipping updates extremely fast to end users without distro build systems and update policies, but the users who participate with those repos could be closer to the in-development versions, while users subscribed to updates on their favorite distros would receive them normally through stable update repos.