2 truenas systems-how to sync site1dataset1->site2dataset2 & site2dataset1->site1dataset2

[xinafoid]

Have 2 TrueNAS systems, each with 2 datasets in case one gets attacked by ransomware. TrueNAS at site 1 will have site 1's data on dataset1, and TrueNAS at site 2 will have site 2's data on dataset1. I want to create a cross-site sync:

syncing site 1's dataset1 with site 2's dataset2

syncing site 2's dataset1 with site 1's dataset2

Each site's dataset2 will be the backup of the other site's dataset1.

1. is this possible? if so, can I use rsync, and have each TrueNAS server act as both a push and pull? or should I look into something else? Syncthing? Anything!
2. is having 2 datasets in the first place enough to protect a cryptolock from traveling between both of them?
3. site 1 dataset1 has 400gb & site 2 dataset1 has 600gb, both are growing by at least 1gb each everyday. every Saturday a full synthetic backup is taken, and everyday an incremental is taken, is this too much data for rsync to handle synthetic fulls on weekend?

Background: Veeam B&R community takes synthetic full backups are taken every Saturday and incrementals every night of site 1's data. Same setup for site 2's data. I have dataset1 at each site being populated by the backups synced via Windows SyncToy 2.1 from Veeam's local backup directory and TrueNAS's SMB share (using separate non-admin local account only). Since cloud sync to Dropbox API is taking forever to sync, I figured setting up a dual way sync of different data to each location would solve the need for off-site backup locations.

 

[xinafoid]

Also, site 1 and site 2 are VPN'd together.