> Don't see how... Nftables is set up once and then left alone.

Same thing for a router configuration to accept inbound wireguard requests on a home network with dyndns. You set it up once and are done.

I see the benefit of the bounce server if you operate a network in an environment where you don't have the ability to control the router config; however, when you do have the ability to update firewall/router config, then I'd prefer just setting up a domain name and avoid the dependency on a third party server.