Database migration across different operating systems

We are in an unusual circumstance, where we need to move all of our Postgres 10 databases from their homes on servers running FreeBSD 11 with ZFS to servers in another data center running Red Hat Linux 7.6 (also with ZFS), with minimal downtime.

I understand that the recommended, safest, approach would be to dump/restore. We intend to do that wherever possible.

However, we have some databases that require high availability/minimal downtime that are also very large. (50 TB, for example)

Because we use ZFS on all of our current FreeBSD database hosts, one idea that we are exploring is to use filesystem replication to move the data ahead of time, and keep it in sync. Then we could start the databases on the Linux hosts at any time and it would be up to date. With that option, there’s almost no downtime.

We’ve tested this procedure on a small database, and it starts, it runs, returns queries. There seems to be no issues.

Is this a reasonable approach? Are there any known concerns/things to investigate before choosing this course?

If it helps:
The cpu architecture is the same on both hosts, and we’ll be running Postgres with the same version and same build options.

Many thanks,
Natalie