People wanting to make gadgets using Bluetooth is a big one and I have been using Nordic Semi line of BLE SoCs very succefully.
Most of the business lately has been coming from a couple of companies that I made some work for and keep requesting changes or more features. I had to disable my Upwork profile as I didnt had the rrsources to keep up with the projects coming from there, even after upping my rates a few times.
I've spent the last year coming up with fun projects of my own, based around ESP8266 devices, and while I don't think I'd ever want to make a career out of it there is something very refreshing about developing in such constrained environments.
It always reminds me of writing code in Z80 assembly on my home computer back in the 80s.
looks like a few other skills have depreciated too
It was very good pay at the beginning but it hasn't keep up and now it's not that good (to bad either).
A few years ago I started playing with electronics (Arduinos, Raspberry PIs and stuff like that). After a while I started looking and picked up a few easy jobs related to that in Upwork as a way to do something different as doing the same thing for 15years can take it's toll.
Shortly after I was picking more and more advanced jobs. I picked a few big clients and moved them off Upwork. I'm now doing advanced embedded system programming and electronic design as a side gig on weekends and afternoons and making more money than my main programming job (which I can't seem to be able to leave).
And that's the story of how I found an alternative to my comfortable job. If I ever leave it I will never go to an office again, I will just expand my embedded freelancing.