The benefit of local-first means you’re not incentivized to sell your cloud offering, so you can just give options. Sync with iCloud, Google drive, OneDrive, Dropbox, Mega, SMB, SFTP, FTP, whatever you feel like adding support for. And since local-first usually means having some kind of sane file format, you can let “advanced” users manage their own files and synchronization like people have been doing for the last 50 years.