There is an exiting thread on the subject. All the erm… truth… is in that thread.
As a rule, it’s better to post in the existing thread than to create an new one. It makes things simpler and more organised.
Short answer to your question is: rekordbox 6 is not ‘unsupported’ it’s just that Pioneer yanked the XML export from their software. I’ve made it clear that I won’t reverse-engineer database formats, even though I could, because it’s illegal in many countries and I prefer to do things legally.
I don’t have any more news on this right now but I am looking to see if there is asolution and will announce it in that thread if one does come up.