Too Long; Didn't Read
The Product Design Process is one of those questions that is done differently everywhere. The product design process is a process that is different everywhere. When you are starting out, you tend to change processes every day, until the team figures out which processes are the most efficient for them to deliver faster. For design products at small startups, it usually means that the team can re-design pages/flows on the fly in their code, view that code in browser debugger/inspector, and iterate again.