https://protonvpn.com/pricing
https://account.protonvpn.com/signup?plan=free&ref=faq

https://github.com/ProtonVPN
https://github.com/Rafficer/linux-cli-community
    https://protonvpn.com/support/vpn-config-download/
    https://protonvpn.com/support/wireguard-configurations/

https://protonvpn.com/blog
https://proton.me/blog/news

https://protonvpn.com/download-linux
    ubuntu, fedora
https://protonvpn.com/support/linux-vpn-setup/
https://protonvpn.com/support/official-linux-vpn-fedora/

https://protonvpn.com/download-firefox-extension