Wireguard tunnel via TCP

Installing and Using OpenWrt Network and Wireless Configuration
26

Mmmh, a quick search revealed:
https://forum.openwrt.org/t/solved-gre-tunnel-routing/25644

https://openwrt.org/docs/guide-user/network/tunneling_interface_protocols#protocol_gre_gre_tunnel_over_ipv4

and

https://openwrt.org/docs/guide-user/network/routing_in_gre

But you will need to rent a server/VPS somewhere "in the cloud" to terminate your GRE tunnel...

Personally, I have no first hand experience with GRE (or wireguard) so I will not be of much help from here on....