I was checking in to see if you were able to get this working? I’m attempting the same thing but am having issues. I have added the SRV and TXT records to GoDaddy DNS.
I’m not sure if it’s a settings issue or related to one of these issues with the discovery service:
TXT Record ( Does GoDaddy Require the Public key to be split ? )
rocketchat-public-key.subdomain1.mydomain.app -----BEGIN PUBLIC KEY----- REDACTED -----END PUBLIC KEY-----