and as these are Xserve 3,1 are on the HCL for ESXi 5.5. Therefore I can legally accept the Apple EULA, and install Apple macOS Virtual Machines on them, because they have an Apple badge (Apple hardware).
If you do not have an Apple badge on your hardware, you are in breach of the Apple EULA. (Please do not ask me, because this cannot be discussed on Experts Exchange)
Consider (quotes from the above article): Direct deployment of Microsoft 365 Apps isn't supported on Windows Server 2022 as it's a fixed, non-changing operating system.
So that means no one would likely install RDS Session Hosts on 2022, Microsoft's newest Server version.
Microsoft 365 Apps is supported on Windows Server 2019 and Windows Server 2016 only until October 2025.
This means that, even though the server OS in the case of 2019 will be supported (through Extended Support) through 2029, it will become unable to host sessions for users starting in October of 2025.
Microsoft's solution for those requiring in-house session hosts is Azure Stack HCI. Which on a single 16 core host would run not less than $530 per month. For an ability that USED to cost as a one-time fee every 5-9 years, a server license ($1000), RDS and Windows CALs ($200/each). Think about it. An RDS solution for 25 users would cost $6,000 once every, say, 6 years, will now cost $39,000 to run on prem with Azure Stack.
Or your could migrate to Windows 365 and get a basic Windows machine (D2 V3) for just $540 per month (or so, on a 3 year commitment with Windows License), or also $39,000.
Please if you think this is reasonable... or I've got …