Are they any good/worth it?

Assume you mean cycle specific brake cleaner as opposed to car types?
I personally don’t think there’s much difference, but use the bike stuff anyway. Usually Motorex as it comes in a bigger can.
Some say the car types contains corrosion inhibitors, but have never managed to get it confirmed anywhere.

does it stop squeaking?

Not always, but will depend on what’s causing the squeeking.
If it’s an alignment issue, then no amount of cleaning will sort it, but if it’s contamination then possibly.

IPA [not the beer] is the sort of thing you want

Hot soapy water & a Scotch Brite pad is just as good though – although someone’s bound to say that will melt your bike

Is her indoors nail polish remover any use, main ingredient is Acetone iirc?