The typical switches supplied as limit switches in the KOP over the years worn are "push button" switches that just have a lever that trips them.
Here is an assortment of some switches that would be commonly marketed and sold as "limit switches".
One of those could certainly be used as your "belly" switch, as is.
There are a number of ways to make it "latch" in the depressed position. A simple method is to have it activated by a lever that has just enough friction in it's mounting hardware that the spring in the switch can't over come.
In addition the GDC went back and removed the "that fits in a wall box" from the definition of "common household light switch". So that opens up a bunch of switches that might be used on lamps.