FP2 Fairphone Open 19.11.2: VPN?

I’m looking for a VPN on my FP2 with OS Fairphone Open 19.11.2
I tried Protonvpn, but did not succed: “Gerät nicht unterstützt”
Is there a possibility to install protonvpn or another app? I have difficulties to find a working one in F-Droid.
Who can help me? Thanks!

VPN is generally a paid-service,* which VPN provider you payed for and are you trying to use?

F-Droid has some clients that work fine. OpenVPN works as far as you have an account with some provider, of course. Then there’re CalyxVPN or RiseupVPN, which are preconfigured apps with the providers of the same name.

There are also more advanced options, like Orbot (uses the Tor anonymity network, and you should learn how to use it properly to stay anonymous) and Wireguard (stable new promising tech, but still considered pre-release software).

*= except if you host your own, which is not likely due to the question

I pay for protonvpn (works perfectly on my computer), but trying to install it on my FP2 failed.
On protonvpn I just click on connect and it works, OpenVPN requests - as you mention- an account with a provider: What provider?