> I'm sure Pi Hole will have DoH support ...
We'll see.
Pi Hole uses DNSmasq as its DNS (and DHCP) server, and the few DNSmasq mailing list threads I've seen on the topic seem to indicate that the DNSmasq developers are not interested in either DoT or DoH. One said that it would be difficult to implement because of architectural issues IIRC.
It may be necessary to use a front-end proxy: