Coffee powder is not instant coffee
No. Coffee powder is roasted coffee beans, ground. Instant coffee is coffee that has already been brewed, then dried back into granules. One still has to be brewed. The other has been brewed for you.
This is the first thing worth getting straight, because everything else depends on it.
Coffee powder
Roasted coffee beans, ground to a chosen fineness. Nothing has been extracted from it yet. All of its flavour and aroma are still locked inside the grounds, waiting for hot water. This is what goes into a South Indian filter.
Instant coffee
Coffee that was brewed in a factory, then had its water removed by freeze-drying or spray-drying, leaving soluble granules. Add hot water and the granules dissolve. Nothing is being extracted; something is being reconstituted.
Powder has to be brewed. Instant has already been brewed and taken apart.
Neither is a moral position. But they are not substitutes, and a filter will not work with instant coffee: there is nothing left in it to extract.
Curious what this tastes like in the cup? See the coffees.