None of them can run server on port 80/443

Your mobile internet is behind NAT and your WiFI router would need port redir to point external traffic to the phone inside the LAN anyway.

So even if you can run it at port 80 you can't really do that without NAT or tunnel somewhere and if you need that you can just NAT to get it visible on 80 from the outside

It's mostly imaginary problem

I don't need website to run on IPv4. Almost every mobile provider has IPv6 deployed here in India. With IPv6, there's no issue of NAT.

But you can run a server, register a domain, and send http://quaintdev.com:8000 to your friends and family, right?