It's quite incredible that Samsung would not provide compatibility between the only free, full-featured file transfer client for Samsung and the S10 series.
Smart switch is no alternative to SideSync. Android File transfer also is not. It is also buggy and basic. In fact, I have never been able to get AFT to work with *any* of my Samsung handsets. Consequently, S10 users have little recourse but to experiment with the numerous third-party full-featured file transfer solutions. There is no clear way of telling which of these are bona fide or not. They also tend to be over priced, costing $40/£40 for a license to access their complete features on average. This situation is unacceptable. I can't imagine that competitor handset manufacturers would permit this situation to arise. Can you either make sidesync compatible ASAP or provide an alternative file transfer solution for S10s.