My Mercury remote uses a toggle switch. One way for off, the other for on.
Kill cord plastic loop goes over the toggle.
Covered by a small plastic box shape to prevent the plastic loop on the end of the kill cord falling off but open on the bottom so the cord can come off after operation so you aren't tethered to the boat.
https://www.ebay.co.uk/itm/Mercury-O...-/202701173233
Whether you could rig something up like that as the wiring would be easy.