in terms of negotiating the problem of NAT what we need is services that give people IPv6 addresses on their devices, and anyone connected to this can be routed inbound via the hosting services

you can get a plain IPv4 inbound route with very little configuration on a VPS using wireguard as the client side outbound tunnel and all traffic for given IP/ports can then find the gateway and pop through the tununel

it's a little outside of my experience area but i know in theory it would be possible to make a routing service that lets you attach a number of IP addresses to a network with like 10gbit, 50tb traffic and make a profit on proiding users with 10 or more inbound routeable addresses, more, if you include reverse proxying as well as port forwarding

it just has to be charged on the basis of bandwidth mainly, to be economical, as the bigger your server/cluster capacity the more the bandwidth factors in the cost, and routing is the cheapest server hosting service for actual hardware requirements