For me, the first thing I’d do is clear my family of all debts(or whatever financial issues) there is and then the second thing i’d do is buy a hundred Siomai for me to eat
What are you buying if you won One billion dollars?
Start a nonprofit open source IoT hardware company. Internet-connected smart devices and appliances are cool, but not the way they are implemented now. I’d base everything on common hobby chips like ESP32, AVR, and STM32. Every single device would have a completely unlocked firmware upload port.