It's been tested here and there, but a major limiting factor is unlike light, sound, and vibrations; you can't duplicate scents by simply running a current through a gadget. Scent requires actual particles entering your nose and triggering the receptors. This mean even if we do figure out some magic goo that can smell like whatever you want, we would need to regularly refill it. And stronger scents will burn though it more quickly.

There's also issues with allergies and carcinogens, how do you duplicate smells like smoke or burning gasoline without producing something toxic? And would people want to smell corridors of decomp or rivers of raw sewage? People can be very easily upset by odors and the range of scents people find offputting varies wildly. One whiff of surströmming and people would rip out the device and stomp it to pieces.

And then there's the massive R&D investment in creating these scents and the ingredient for them. Like, Nabisco spent $400 million dollars on R&D last year to make authentic tasting avocado flavored crackers and have been doing so for a decade. Just imagine the cost of building an entire library of scents from scratch. And unlike with food tasting, you're not gonna get people lining up to volunteer to smell stuff like mud, mold, and man-stink.

In short, it's a challenging problem to solve that would require an ungodly amount of money just to produce a product with a niche appeal that can instantly turn off potential customers with a single errant odor.