I hope you can find the supplies to tube feed. It is the safest and most efficient way to get the appropriate amount of food into a sick bird and it gives them the fluids they need which are vital as well.
In an emergency, if you can't source the right size tube quickly enough, you can hand feed the Kaytee baby bird feed direct to the beak. It's not as good as tube feeding and it takes a lot longer but it is an alternative safe way that can't aspirate them. It's a lot more doable with a chick than an adult bird due to the amount of food required.
You can mix it up to a consistency that's solid but soft and squishy. I've found that if you mix in some ground up chick starter and some raw egg yolk, you can make a nice consistency that's possible to roll into small pellets, about the size of a pea. Then it's just a case of gently placing them one at a time into the beak. I imagine you could do similar with just chick starter and egg but the Kaytee baby bird feed is really great and it has a lot of additional micronutrients and probiotics in there as well.
If your peachick isn't drinking, it's not ideal because the hydration is as important if not more so than the food. It just might be something to buy you some time while you source supplies.