All my ideas would require both more time and more money, plus business skill and a desire to do any kind of business on my own....

One thing I'd love to work on is more modular home automation. The "smart" part does not need to be the same as the actual appliance or bulb or lamp.

Everything has a computer in it now, which makes things hard to repair, but really it should be way easier to repair than ever before, if only things used more standard modules.

There are modular electronics systems, but none of them are really meant for consumer or industry use.

For some reason, even switching 12v on and off is still not a solved problem.

At best you get an IoT relay module, which uses an old school mechanical relay with zero protection or diagnostics onboard.

Nobody makes a cheap board with an ESP32 and a few current protected, PWM capable barrel jack outputs, with current sensing and voltage monitoring, flashed with ESPHome.

A turn-based or real-time strategy game wherein your civilization advances via diplomacy (spies & ambassadors) and stealth operations (commandos, special forces, etc)