https://tailscale.com/kb/1054/dns#nameservers
and
https://tailscale.com/kb/1114/pi-hole#step-3-set-your-raspberry-pi-as-your-dns-server
Set tailscale to use your dns server to resolve your services (or all traffic if you prefer). Assuming your dns server is on 100.x.x.1:53, then put 100.x.x.1 as a nameserver.