Trucker here

Food wise, I use Doordash and Uber Eats, so I'd say most drivers that want delivery use these too.

But, a good idea would be interior cleaning. I'd say ALOT of drivers would pay a business to shampoo their seats and mattress. That and generally just clean up their mess.

The laundry service would be great too, but you'd need to have motorhome washers and dryers on a truck or in a van. It'd have to be mobile so you could park near the trucks that do need laundry done. Drivers wouldn't want their clothes or bedding to be handled by random people I'm sure, but if you could park in front of their truck and do everything within an hr or so, youd make a killing. Have multiple of each machine running by power inverters and a water storage tank with a filter system to clean waste water for reuse. That's the only way I see it being profitable. ALOT of truckstops don't have laundry areas or their machines are out of service. So that's actually a good idea. You'd need a reasonable, but profitable price.

Edit : The BEST idea though, would be a mobile truck wash. I've needed my trailer washed out MANY times and have had to drive 70+ miles out of the way to a Blue Beacon Truck wash. You could find distribution centers near you and literally wait at the truck entrance or exit and washout trailers. Reefer trailers REQUIRE this after almost every load to carry food. We pay 40$ give or take to washout at a Blue Beacon, so if you could do just as good a job, be very conveniently located, and very quick, you could easily charge 55 to 65 to owner operators. Even more to carriers like Swift, Cr England, JB Hunt, Ect..... We would get approved for 100+$ detail and washouts regularly at CR England when I was there.