I tested organelles HDMI port with a few SCART and VGA adapters and it seems that all you really need is for the adapter to have a 5v power supply (usb or otherwise) - clearly the organelles HDMI port, like those on Raspberry Pi’s, doesn’t like sharing too much electricity. So, if you want to use an old computer screen, VHS player, whatever with the Organelles (and probably the ETC’s) HDMI port, just use the appropriate adapter - but choose one with it’s own power source.
Been making some vhs stuff with OTC just now, looks ace