28,659 questions
To enable WSL2 (via the Turn Windows features on or off or dism or Enable-WindowsOptionalFeature command), we need win10 1903 or above. WSL is a win10 feature and mostly there is no official statement additional cost is required for the WSL feature. It seems we only need the win10 licenses.
You may contact Microsoft Licensing Center.
https://www.microsoft.com/Licensing/servicecenter/default.aspx