Many years ago I took a lens from an OLD pair of "field glasses" ... I doubt that you could put the binoculars back together again and have them work as well as before.
It's not absolutely necessary to disassemble a bino/monocular for making fire if nothing else is available for that. Just play with the focuser a bit to make the sun image appearing as a sharp circle
on a piece of paper, and then move in some dark colored tinder as close as possible to the eyepiece. Be careful enough not to damage the eyepiece as the tinder light's. Also this way it seems to work better, in case your bino/mono objective lens is smaller than 1 inch.
(Oh, and watch the second eyepiece from burning something unexpectedly if using a BINOcular!)
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some info here)
I'm carrying the SpecWell (Japan) 8x20 monocular with extra short focus most of the time. Reasonably portable, wide field of view, and fantastic clarity. It works very well as a microscope at 12 inch distance too. Used it a couple of times to melt the ends of paracord.