I'm going to chime in here with my experience, even though I've not been active in this forum since I downgraded to Mojave. t
Before I downgraded, I could get all of my iPod Classics to sync with Catalina. I can't speak to anything beyond the 10.15.2 version though. I didn't downgrade because I couldn't sync, I downgraded because the behavior of my iPod was unacceptable. I've outlined those issues elsewhere in this same thread, I believe. The issues included, but were not necessarily limited to:
Failure to remember location of partially listened podcasts
Failure to stop playing at the end of a podcast, despite being set up as such
Loss of chapters in my audiobooks
I'm perfectly content with Mojave. Someday, I may install Catalina on a second partition and occasionally try to sync from there; however, I have ZERO confidence that Apple has any interest in supporting such legacy devices.