Modern VPNs based on wireguard can do direct connections with hole punching. It's just a lot more work to setup on your own, or you have to sign-up to a SaaS like tailscale and use their relays, and they'll do the hole punching for you.

Here this is a decentralized network with a lot of existing public relays. But in principle a VPN can solve a lot of the same problems. It's just that commercial VPNs are not decentralized, and doing your own wireguard setup is a pain.