Gregory's Server
Update 2, I have set up a DHCP server again :/
I am still advertising only the DNS64 over SLAAC so I can make some fun graphs of apps with hardcoded IPv4 DNS servers. The only issue with this setup: systemd-networkd may be able to do everything but it falls apart way too quickly when just leaving it a night, I'll just setup udhcpcd again.
I have also considered the overkill solution: run a dynamic routing daemon on every Pi infront of a PC, setup jool with IPv4 -> NAT64 there and do NAT64 -> IPv4 at the gateway.
Honestly, the only reasonable solution to deal with applications that don't know what an IPv6 address is here if you ask me /j