the "sync" isn't really a problem. you are making too much out of sync. passwords don't change much. you don't have to change/edit your entries every other week.

i keep a live copy on my phone and a copy on the desktop. if i have to add an entry, i add that to the phone and use kde connect to send that file to the desktop. takes 2 seconds. when i open the desktop keepass, i am greeted with the updated file so its not a big deal.

with keepass there isn't an issue with trusting vendors. they do not have internet access so what are they going to exfiltrate?