Windows Server OS based VDI with SPLA

Question

Seeking clarification on the licensing requirements for creating a virtual desktop infrastructure (VDI) using Windows Server under the Microsoft Services Provider License Agreement (SPLA).

Fact: Win 10/11 desktops not allowed

SPLA does not allow me to create a service based on a Windows client desktop.

Fact: Windows Server VDI supports only Win 10/11 desktops

Windows Server VDI, technically, does not support the creation of desktops based on Windows Server.

RDS as a VDI alternative

SPLA does allow us to create desktops based on Windows Server. Using the built-in features offered by Windows Server, the only way to provide a Windows desktop in SPLA is RDS Session hosting. Needless to say that session hosting does not offer the same kind of isolation as VDI.

Windows Server based VDI

There are third party solutions, however, that do allow the creation of a virtual desktop infrastructure using Windows Server OS, such as Citrix Server VDI. And there are third party DaaS-offerings that are based on Windows Server, such as Amazon AWS WorkSpaces.

Licensing of Server based VDI

When using third party tools, it's technically possible to build VDI based on Windows Server. But how to properly license it?

If I read the Windows Licensing section of AWS Workspaces, and in addition compare the prices between Windows and Linux Workspaces, it becomes quite clear that AWS does not license the server OS for a VDI VM but only the RDS SAL.

However, since AWS is a Microsoft listed provider, their licensing terms might differ.

I'm planning to discuss this with Citrix, too, but I was still hoping that I can get an answer from someone closer to Microsoft.

Question

Factually, when talking about VDI, we're talking about isolated VMs. It's clear to me that a regular Windows Server VM has to be licensed per core of the physical bare metal server. Is there anything in the licensing documents or in other public statements made by MS that suggests that if such a Windows Server VM is used exclusively for the purpose of providing a Windows desktop to a single user, and that the VM will not be used for any other purposes, the per-core licensing does not apply and instead a RDS SAL will be sufficient?

Afterthought

If it cannot be confirmed that a SAL would be sufficient, then under no circumstances can we or any other non-listed provider ever offer cost-efficient, fully isolated Windows Desktops (as a service).

My goal is not to compete with Azure or AWS, my goal is to offer an alternative for a very specific use case. But if alone the Windows Server licensing cost will be $80 or more per VDI VM while Azure/AWS charge about 20$ for the virtual desktop VM including all licenses, then this makes zero financial sense.