Suggestion for Alt-Shift-S sequence on a tablet with no keyboard

Wondering if you have any suggestions for ways to enable the admin menu without an attached keyboard.

Can it be called from command-line?

Assuming you're using a virtual keyboard, it can be called from that. You can use the Windows 10 Touch keyboard in most cases.

Otherwise, you can always use the Inteset Remote Management Services to do what you need (ie: disable Secure Lockdown.)