You can read around the parallax propeller 2 forums for an idea of what it takes on the low end - they were very open about the process. IIRC they have one guru who does software and Verilog, one who does RTL layout (term?) and the rest are support staff who do other things at the rest of the company most of the time (PCB designer, assembly, sales, HR, etc.)

The raspberry pi pico team also did a good podcast episode talking about this - I think it was a podcast called innovation coffee or something like that. Hosted by a guy from ARM Europe.