I shipped a small change on rolld today after seeing @chrisshank.com's community proposal. Play permalinks now include additional metadata:
<meta name="at:canonical" content="at://did:plc:4i6hvdii3km3kbnj3losmwnt/at.rolld.play/3mrlhhgx7os2x" />
<meta name="at:author" content="at://did:plc:4i6hvdii3km3kbnj3losmwnt" />Profile pages carry the at:author line on its own, since a profile is a view of a person rather than of one record.
If you're building on ATproto, check the detailed proposal here. It may be something you want to implement too!