Run terminal/login shell when desktop is stuck

It helps to have a separate admin account for such cases so you can log into that one and terminate whatever process is stuck on your main account.

When the GUI is hung, force quitting apps is less preferable than using ssh to remote in from a phone, tablet or another computer. You would only have fast user switching as another “work around”.

I tend to keep the Terminal running always, so that in the event of one app locking up, I can usually switch to the Terminal somehow.

But it's very rare in MacOS for the entire UI to freeze up.

If this is happening regularly, then I'd suggest trying to diagnose and fix the problem so that it doesn't happen, rather than 'managing' it after the fact.