Is Windows 2019 Essential good for a non-domain joint Veeam backup server?

No. Server Standard.

Windows 10 is cheaper.

I think Desktop OS has a limit on the number of inbound connections though? Would that be appropriate?

@Philip: why "no std"?
Since it is for a veeam backup server: the number of inbound connections (rdp??) should not be a problem.

@andyalder: I don't know if Veeam would work on Windows 10?

It's a supported platform according to https://helpcenter.veeam.com/docs/backup/vsphere/system_requirements.html?ver=95u4#backup_server

Difference between Windows Server and Workstation have always been fairly small as far as being an application rather than infrastructure server.

Essentials has a set of very specific terms, much like Small Business Server before it, for its use.

Windows Server Standard is the best fit for this. Please don't shoehorn Essentials in to where it does not belong.

@andyalder Thanks for the clarification on install locations.

The limit I was trying to remember is this: Maximum Concurrent Connection Limit

It's 20 for a desktop OS. So, I guess it all depends on what's being backed up and how many incoming streams are needed to the B&R "server".

Just make sure it has ECC memory please. :)

I think your connection limit is just for file/print/IIS.

Thanks for the info guys. I'll see if I can make it work on a simple Windows 10

I finally chose Windows 2019 essential and it is working great and costs half the price. tx!