I don't think that it's a foregone conclusion that IPv6 "failed". I'm rolling out services on v6 only now for my hobby projects. Just next week, I'll be switch

I don't think that it's a foregone conclusion that IPv6 "failed". I'm rolling out services on v6 only now for my hobby projects. Just next week, I'll be switching over our company backups to v6 because I can have a dedicated port 22 on the backup machine instead of port forwarding. I've been running company VPNs v6-only (inside the VPNs) for some years now. Our corporate services and my private hobby projects are all v6-enabled (in addition to v4), the latter since 2018 or something. A non-techie friend of mine has CGNAT at home on v4, and simply used his consumer-grade router to open a port to the v6 address of his NAS. He and some friends and colleagues from his Uni been using that for half a year before they stumbled into a situation where somebody had no v6 address and could not access the NAS. I think we're getting there fast.