You're correct. As @Osiris mentions (thanks!) ACME (RFC 8555) provides no challenge types associated with identifiers other than DNS type.
We have no plans to support these Subject Alternative Name types. Beyond the challenge of how you would validate them we are forbidden by the CA/Browser forum baseline requirements from including them in our certificates. See Section 7.1.4.2. "Subject Information – Subscriber Certificates", specifically 7.1.4.2.1 "Subject Alternative Name Extension":
Each entry MUST be either a dNSName containing the Fully-Qualified Domain Name or an iPAddress containing the IP address of a server
Including an OtherName type Subject Alternative Name with the OID for SRVName or XmppAddr would be a misissuance under the BRs by my reading.
Hope that helps explain the situation,