If you're comfortable with the large and ever increasing risk of loss (by adding drives without adding redundancy) then Synology is probably indeed a better match for your use case then ZFS.

I don't really understand why pay for dedicated NAS hardware if reliability isn't priority #1, but that's me.

Personally, for stuff that I care about but not quite that much, I just keep on the SSD on my laptop. It'll very probably be fine but there is risk of loss (same as Synology).

For the things I care deeply about, they go on the ZFS server with tons of redundancy, snapshots and backups. I'd never trust the truly precious data to anything other than ZFS.