A big thing is missing. InDesign has supported a long time making Accessible (see NOTE1) PDFs. Affinity Publisher has no support for it, one must convert the PDF to accessible. I guess some bad words will appear if the whole conversion must be repeated after an edit in A.Publisher.
The problem is significant because in EU at least all public PDFs created with state or city funds must be accessible. That covers for.ex. schools, universities, authorities, public services and anything which is paid by them.
Fortunately it doesn't cover all archived stuff.
NOTE1 Accessibility means certain visibility things (=colors, sizes) and machine readable structure of PDF. Term PDF/UA covers the machine readability things. It's not a new PDF format, only a restrictive set of rules how PDFs should be constructed internally. I guess software developers work hard to make PDF/UA construction possible in layout design programs. I have seen some serious attempt in Adobe InDesign, OpenOffice Write and MS Word. Adobe has been in the game at least 8 years. Adobe Acrobat Pro and Foxit PhantomPDF Business have some serious attempt to support Accessibility building, checking and fixing for PDFs.