You can transfer a database between the two operating systems using
Backup & Restore. Note that PostgreSQL doesn't have a merge function so if you want the exact same database for both machines you'd need to import into each of the databases those hands only the other one has and then you could keep both your databases manually synchronized with a
setup like this.
You can also export/import notes via 'Database -> Notes' which is OK if you are merging different notes from two databases or if you only ever transfer data from one database to another however if the same note exists in both databases then the note text is appended meaning that it will be doubled up so this isn't ideal if you are going to import notes from one database into another and then back again e.t.c so if one of the machines is always on even when not playing poker from it you could have both machines sharing the same PostgreSQL/database
on a Local Network.