edit: I should have specified, it's just a different edition of Windows 10, like Pro, Home or Education.

The Long-Term Servicing Channel (LTSC) is made for enterprise and big companies and it comes with useful features for our situation, most importantly:

1. It gets updates beyond the official End-of-Life for consumer use.
2. It comes with less poz preinstalled.
3. It's easier to disable additional poz than on Home or Pro editions.

You correctly guessed that it's not free, however they are never going to sell it to you.

You will need a special crack but if my info is correct that should have become fairly easy to obtain nowadays.

The Long-Term Servicing Channel (LTSC) is made for enterprise and big companies and it comes with useful features for our situation, most importantly:

1. It gets updates beyond the official End-of-Life for consumer use.
2. It comes with less poz preinstalled.
3. It's easier to disable additional poz than on Home or Pro editions.

You correctly guessed that it's not free, however they are never going to sell it to you.

You will need a special crack but if my info is correct that should have become fairly easy to obtain nowadays.