> Is there a decent way to buy this LTSC edition of Windows?
If you are a student or work at a supported educational institution: I think Windows 11 Education is to my knowledge basically identical to Windows 11 Enterprise (at least for Windows 10, this was the case). In these versions, you can use LTSC updates if you want.
There's two flavors of Windows for Education. One is more or less Windows Professional, the other is more or less Windows Enterprise. Both disable some stuff by default, I think the Microsoft Store and Clippy/Cortana/Copilot, maybe some other things... But you can do that with policy editor too.