RDS or VDI running on/from Server 2019 fully supports the OneDrive client sync, INCLUDING Files OnDemand, for persistent image types.
If I was running an RDS server, in todays world of cheap and fast storage, I’d seriously consider moving to persistence of some type for simplicities sake.
You are also correct that you can use FSLogix to enable non-persistant sessions on Server 2019 for either RDS or VDI which fully support OneDrive+FoD. FSLogix can be licensed a lot of ways, but one of the common ones will be to use Server License + User CALS + RDS CALS.
A few other thoughts:
- You’ll need to be using ProPlus for your office licensing
- You’ll want to keep all your MS licensing under SA
- Regularly keep things updated (I’d patch in real time and do feature updates yearly)
- I would seriously consider using Windows Virtual Desktop (WVD) instead of onprem RDS if your access pattern allows it
- WVD runs off Windows 10 instead of Windows Server, and gives a much better desktop experience and increased app compatibility
- M365E3, available inexpensively to NPOs, gives you all the licensing you need for WVD
- You only pay for the user compute in azure, access to onprem data possible via VPN tunnels in azure
I have pulled a few things together for you to review.
Hopefully this helps.