@johnpoz first let me say thanks for all your help. We've established and I've implemented the following:
alias' and firewall rules , despite the option to do so, realistically can't and shouldn't combine IPv4 and IPv6. Instead use separate alias' and rules to handle NAT IPv4 as well as GUA IPv6.
The LAN domain name shouldn't be the same as the public domain name, a recommended LAN name is home.arpa.
public-facing servers at myhost.mypublicdomain.com can be accessed from LAN or WAN using firewall and NAT rules. From the LAN only, they can be resolved by pfSense DNS using myhost or myhost.home.arpa. This is an acceptable and expected result. Browser and app URL configuration can function regardless of connection to LAN or the internet at large, pointing to myhost.mypublicdomain.com.
private servers not firewalled and NAT'd are accessible only from the LAN at myhost or myhost.home.arpa, which is also expected. Remote access to these private servers, if desired, would be implemented with OpenVPN to the LAN. They were never expected to be available at myhost.mypublicdomain.com.
All that said, I do have flaky behavior from the Homeseer4 server, where the Android app can connect from the WAN using myhost.mypublicdomain.com, but fails to connect from the LAN using the same FQDN. As this behavior does not replicate with any other of the several public-facing servers on this network, I'm ascribing this to a flaky old Android app.