I couldn't get sync to work between my old Windows laptop and my Android.
Windows 11 destroyed my old laptop, so I switched to Apple Mac.
Sync didn't work at first, so I deleted all bookmarks and cleared all of my history on the Mac. Turned Sync back on and N and now Opera all of the bookmarks from the Mac Trash folder were moved to my Android but nothing synced from Android to Mac, which is what I wanted.
Opera Sync is not a feature, it's a wish un-granted.