I've tried to run an IPv6 only box on Hetzner 2-3 years ago. Didn't have a problem with the platform, but with RedHat because subscription-manager didn't work over a IPv6-only stack.
Around the same time, I think the Photoprism image also didn't work on IPv6 because of Traefik
When I accidentally had IPv6 only for a new Windows box it was very apparent what was a priority (worked regardless) and what wasn't important (only began working once I had IPv4 and everything fixed too).
Baked in advertising? Works with any network. The option to turn off the baked in advertising? That needs IPv4.