OpenVPN is a protocol. If the VPN provider supports it, you set it up in your own client that supports OpenVPN. Using a VPN provider that requires you use some proprietary app is madness.

I recently signed up for such a service, in order to get my Nintendo Switch online for multiplayer gaming. My home internet connections sub-let from the landlord and could be considered semi-hostile -- not able to connect to peers on the Switch due to triple NAT, and I suspect some QoS throttling as well. The VPN solves my routing problems, but if anyone has a suggestion for another option here I'm all ears.