Yes it should be possible to run the pump through a switch. I did this for my mates Porsche 924 as it needed the pump running to prime the system for a few seconds before he started it. This was simply fuel running back to the tank as it stood, a symptom of a worn out fuel system. Unfortunately the Porsche fuel relay would cut out almost instantly if the engine was not running, so it would not prime.
He now has a hidden switch which also, as you say, acts as a security device.
You may want to fit a "crash" kill switch in series if you make this permanent fixture, this is performs the same function in a crash as a pulsed fuel relay.
Example
www.amazon.co.uk/dp/B08KTDB8V9/ref=cm_sw..._encoding=UTF8&psc=1
They don't cost much. Best doing all this via a standard relay and use this to switch the pump, again only if it's a permanent fix.
I've not studied the Jimny system so don't know if it has a pulsed relay or it's directly under ECU control. The fact it ran with the temp pump suggests even if it is ECU controlled bypassing does not cause any other issues.
Good luck
Mike
Yokohama Geolanders, Sony head unit, NAUTILUS Air Horn, DRL conversion, Rear cargo space, Elvis Bobblehead, transfer Guard, Indian hanging Elephant, Koni Heavy track dampers, Custom SS exhaust, Voodoo Doll, Adventure Rack with LED ight bar, vintage ERIBA caravan usually attached (yes it's slow)
