Any way to have it always on?
No, I don’t think that is possible. To my knowledge, only IKEv2 has this functionality, but enabling it requires a supervised device with a pre-configured VPN profile. Third-party apps (like CyberGhost) can listen to network events and manage VPN connections automatically, thereby making it effectively always-on, but it is not a complete solution. The OpenVPN app I am using does not offer this functionality (it is actually a very disappointing app).