For medium/dark roast you don’t need to preheat. You pour hot water directly into the deep basket, which has very little thermal mass so the temperature won’t drop much. The basket sits in the portafilter with a handle so your hands are safely away from the heat. Much of the heat loss is to the piston but due to the short contact time (~30s) it’s not much of an issue.

For light roast you do want to pre-heat the piston…and you’d need to be creative for that (I’ve seen some people use candles…). This is when you’d want a Flair 58 with the electronic temperature control.