I went IPv6-only for everything internal. The only thing that’s dual stack is the wireguard server running on the gateway. I haven’t run into any issues, mostly because my Linux distro’s package repository has many IPv6-compatible mirrors (enabled by default). For anything not in the distro’s repos, I build from source and package them up into RPMs myself, so as a side-effect, I don’t have to deal with eg. Github not supporting IPv6.
Even things with generally crappy firmware, like the APC UPS management card, Supermicro & ASRock IPMI management interfaces, etc. have worked fine in an IPv6-only setup for me.