It is up to you to add support for LiteSync on GRDB
You will need to fork it and make it use the LyteSync libraries instead of the custom one.
You can use SQLite.swift with native SQLite interface.
See the last usage example here:
https://litesync.io/en/mobile-database-replication-ios-xcode.html
It supports 3 different ways to access the database
If you do not want the whole wrapper, fork it and remove what is not needed