Still buy your cheese in blocks and hand grate, but sodium citrate is better made at home for sauces I think. Titrate baking soda with a tart citrus juice (e.g., lime or lemon, whatever fits with the dish) over medium heat till incremental juice doesn't induce extra bubbles. You'll have a roughly neutral pH, citrus-flavored solution of sodium citrate suitable for nacho cheese and a variety of other dishes.

I too have experimented with sodium citrate.

I ended up with something reminiscent of movie-theater nacho sauce.

I wouldn't do this in a restaurant but a quick cheese sauce for something like nachos. Just pop some shredded cheese in the microwave with some heavy cream or half and half. Adjust to taste / texture. Stir well.

Mornay, citrate, and evaporated milk approaches work but I'm lazy so I just do the cream approach for "queso".

Yeah it'll melt like that. If you try in things like a cheese sauce for mac and cheese...it melts poorly into the milk and messes with the consistency/thickness.