The Kailh Box switches are the first to come to mind. The slider pushes onto a lever on the side of a box, and the mechanism is inside that box, separate from the compartment with the slider. That is supposed to make them more resistant to dust.
However, I dunno if anyone in the community has actually put that to the test.
The Kailh Box also has a shroud around the stem supposed to also make it harder for dust to get inside the first compartment.
Switches from other manufacturers with just a stem-shroud have also been marketed as "dust-proof" without being significantly different on the inside than a standard MX-type switch.
BTW. There are also some vintage boards with Cherry MX (or clone) that has like a fitted rubber or plastic sheet to protect against dust and liquids (colloquially called a "keyboard condom"). Those sheets would only fit on regular stems: not shrouded ones.
I've had one with a silicone sheet but it impaired key feel considerably, but I've seen police car keyboards with a thinner sheet.
I wonder what the best way would be to make one yourself. Perhaps 3D-print a mould, lay a sheet of plastic bag material and gently use a heat-gun? SIlicone would require a two-part mould, I'd think. Silicone could be thickened to be brushable, but the result would be stiffer and uneven.
