Logical Replication: Initial Snapshot For Large DB

Hello all,

I have a pretty large HA database (2TB) that I need to migrate from EDB
Advanced Server 12 to standard Postgres (12 or 13 doesn't matter).
According to the docs, in Logical replication an initial snapshot happens
in order to synchronize a publisher and subscriber. Will this initial
snapshot work between 2 different versions of Postgres? If it would work,
what sort of system load can I expect for 2TBs of data? The goal is to have
0 downtime, other than the switchover to master on the new version. Also,
besides the initial snapshot is there any other way to incrementally seed
the subscriber DB over a period of time?

Thank you!