For any 20+ years-old readers here, if you ever think/dream about starting a business, you should learn from OP that cash and savings is paramount for freedom and creating a business later on.

> product-focused dev with 10 years experience at a-list startups [...] I don’t have enough cash saved up for significant runway. I’m 35 with family and living in the US.

The earlier you start, the more you accumulate, the more flexibility you have later. I had 12 months runway when I started mine, and it is so valuable not to look for investors and just work on your product/company when you feel pretty confident.