Dear Steve,
Hope you're well, Windows 10/11 and Windows Server 2022 both support running LTSC 2021 on multi-session environments, such as in Azure Virtual Desktop (AVD) or Remote Desktop Session Host (RDSH).
Multi-session allows multiple users to connect to a single virtual machine and share its resources, such as CPU, memory, and storage. LTSC 2021 is supported in multi-session scenarios on Windows 10/11 and Windows Server 2022.
It's worth noting that some applications may have specific requirements or limitations for running in multi-session environments, so it's important to check the documentation of any applications you plan to use in this setup.