LTSC is not legal to run for the vast majority of users and Office is not supported on it. That's not really a solution.

You can buy a LTSC license for a single computer.

https://community.spiceworks.com/topic/2167558-explicit-inst...

> Office is not supported

I mean realistically how many times have you ever had to reach out to support regarding an issue with Office?

Try telling your security department they're on an unsupported configuration and see how long before your higher ups request an audience with you for a "quick chat"

What versions? Would installing something like Office 2016 work?