I think the OP means so that it can be used without an app and so it can be used with Apple's "Always On VPN" setup. Right now I believe "Always On VPN" only works with the OS supported VPNs: IKEv2, L2TP, SSL VPN, and Cisco IPSEC https://support.apple.com/guide/deployment/vpn-overview-depa...

Nope, there are a ton of 3rd party SSL/other VPN clients that use the same frameworks that can be set to always on - the app just has to be written that way.

Consumer VPNs typically aren't.

My mistake! The docs I linked weren't clear about it.

The WireGuard app works with always on.