A toy camera is one that costs less than the roll of film with which it is loaded.
in this case there would be very few. a toy camera as I understand it, is a camera with which I want to play around and not do serious work. although the result might be fantastic and quite be commercially exploitable.
Anything originally produced to sell at a very inexpensive price point. Intended for beginners, and uncomplicated ease of use. Something you can hand to a kid and not worry about and expect viewable images back. Designed for fun, and have looser tolerances in all aspects of use and build.
The creative part of a Krappy Kam is its Krappy Lens - invariably a plano-convex with the aperture mounted too close to the lens. The problem is the rest of the Kam is so unreliable, and usually the worse [better] the lens the more unreliable the shutter/winding mechanism/door latch/etc.. The Empire Baby is probably the worst/best example. It was also my first camera, purchased at the age of 7 for 2s/6d [make it 50 cents] at Woolworths. It cost a lot less than the film and processing that I had to wheedle out of parents and relatives.
Reliable almost-a-toy cameras from Kodak, Herbert George ('Imperial'), Ansco and others had meniscus lenses and correctly placed apertures and produced results that were uninteresting.
'Lens Baby' was supposed to be the answer - a crappy lens for your Nikanoltax - but the prices got out of hand and the lenses never had the right amount of optical charm. I have found a good lens is a Spiratone Portagon coupled to a 2x extender - without the extender there is too much peripheral blur.
A Petzval portrait lens for 35mm would be intriguing.