Parent poster's bio link points to https://www.hellotwist.com/ which does multi-room speaker systems.

What I was going to say before thinking to check the link, is that there must be a wealth of applications available to the instrumentation engineer, using modern microcontrollers without making the full step to Internet of Things.

The smoke alarm with the "I'm cooking for the next ten minutes" button. The simple alarm clock that knows weekends from weekdays, or even your work shifts. The thermostat with a few dozen more available states than the traditional ones and a sane interface. Electric showers that deliver a pleasant showering experience. Smart dumb devices.