Wireguard is your plumbing layer. OpenVPN is an entire application stack. Wireguard is super simple because it's low level. If you wanted to compare something (as a user in terms of feature parity, etc.) to OpenVPN a more accurate comparison would probably be nebula or tailscale (private/mesh network management tools that are built atop wireguard). I'm a wireguard fan and it's true that its crypto is much simpler, smaller, and harder to fuck up than OpenVPN but that is really only something that matters to the security hats.