Is there a software (add-on, standalone, script, whatever) to put the current Firefox (Quantum I think) into fullscreen on a desktop stretched across multiple monitors? It must run on a 2x2 Kiosk mode setup. I've already tried using different software (like ultramon) and browser add-ons for Firefox (like Modern Kiosk), but none of these have worked so far.
The target system is a Windows machine, if there is a paid solution the price basically doesn't matter (if correct functionality can be ensured in advance).