I don’t know if you have Affinity Photo installed, but you could certainly try the 10 day demo if not.
If I look under the EXIF tab for All info, rather than a summary, I can see it includes dc:rights with the relevant copyright information, then below that it has dc:subject for each keyword that I added via Lightroom, which I believe is IPTC.
None of this is relayed in a clear manner that is easy to read and there is no way at present to add or edit keywords in Affinity Photo, though there is a section for description.
One day I would have to imagine they will improve this, but in the meanwhile any user of Affinity software is stranded and a product like MetaImage could really fill the gap for those who want to stick with the native file format.
I adopted the DAM system many years ago, following the methods of Peter Krogh as outlined in his book and I really want to enjoy the advantages of Affinity, but not at the expense of a disorganised image archive.