Is there a system keystroke (interrupt) I can press to force a coredump on OSX? How do I force MacOS to dump the state of the running processes and reboot without the need to open a windows or open a command line?  My system is effectively unresponsive to non-system interrupt activities (keystrokes take minutes to process - holding down the power button works).  Is there a key sequence that can tell MacOS to snapshot state and reboot for later diagnosis?  Does MacOS possibly store a system dump somewhere after a forced system reboot?
Sure. Here is the main list of shortcuts.

https://support.apple.com/en-us/HT201236

First get a sysdiagnose with shift - control - command - option - period

How do you get system diagnostic files from macOS?

Then choose whichever restart or shutdown option you want from Apple’s list.