T-Mobile, a major phone provider, runs an ISP which is IPv6 only. That is, your phone never gets an IPv4, unless connected to WiFi. They offer home access points with a 5G modem and a router; the external address is also IPv6 only.

It works plenty well. I access everything accessible via IPv6, and the rest through their 464XLAT, transparently.

My LAN still has IPv4, because some ancient network printers don't know IPv6. OpenWRT on my router supports IPv6 just fine. Of course I do not expose any of my home devices to the public internet, except via Wireguard.