The developer shortcut to force-end a task is only available in Windows 11, unfortunately, you’re right. I have updated the title, to make this clearer.
To create a shortcut in Windows 10 with the same ease-of-access; you could create a .bat file to terminate the task, and save it to your desktop and if you would like to close the sim easily from the taskbar (since MSFS will be in focus), you can pin it to your taskbar. It might take a little longer to setup but you can also create a shortcut to directly close the sim. If you would like me to make a longer step-by-step guide, let me know.