Re: Windows 7 upgrade to Windows 10
Technically you can, customer needs eligible licenses though that allow to do the upgrade from a licensing perspective.
E.g. Windows 10 E3 subscription in CSP program offers this upgrade benefit when customer has Windows 7 Pro or Windows 8 Pro licenses (Even when subscription is cancelled customer can keep Windows 10 Pro).
Same for M365 Business which includes Windows 10 Business. And of course upgrade licenses via Open also include the right to upgrade.