Hi Olivia,
Then I think you would be surprised by how many users still use, and intend to continue using, ISO XML schemas. For many of them OGC API Records is a novelty to keep an eye on, but not an alternative to jump into any time soon. OGC API Record is a standard for publishing metadata documents, it is native to a generation where JSON is the sovereign format, therefore the only one that is formally mandatory by the specification. However, this does not exclude the possibility of publishing documents in other formats, including XML. Obviously many of us would never want to see XML again in our lives, but that day still seems far away.
There is no XML schema that I know of to include multiple ISO records in a response except CSW, and coming up with a new schema means that it won’t be interoperable.
I imagine the interaction with an OGC API endpoint occurs through a collection that contains all the metadata items, which can be requested one by one in the supported formats (JSON, HTML, XML) and possibly indicating the XML schema (there is a profile paramater for this). Of course this is the only endpoint (item) that should support XML format.
Please let me know what you think and if the end user experience is different.