I believe what counts here is the paint type there is on the frame, not what the frame is made of (although it might be worth it to test if it doesn't discolor aluminum).
Reason you usually need to use chemical stripper on metal instead of heat, like from torch flame, to soften paint, is because metal carries the heat from torch away too fast, paint barely has chance to get hot. Plus maybe it is not a good idea to use flame on bike frame to begin with.
Some paints can resist paint stripper, some give in but need several stripper applications. For steel bike frame, you may want to use small brass wire brush (paint shops sell those) to work the paint off after the stripper has acted. It needs to sit in generous layer on the paint for some minutes to soften the paint but don't let it dry completely. Nothing happens when you do but you have to apply the stripper again. For aluminum, maybe even just use plastic spatula? But if we talk about baked enamel or what is on bikes, maybe the stripper won't work at all or hardly at all. Never done such thing myself but I used the stripper in many situations otherwise.
I am guessing that in the end, if you really want the job to get done, you will need to buy the most noxious stripper, the traditional one. Your choice.
Last edited by vane171; 05-11-20 at 05:54 PM.