Founder is ‘PM on steroids’

Not if the "founder" experience as a founder was micromanaging a startup of 10 people. I had a PM like that once and he was one of the worse PMs I've had.

Founder implies wearing a lot of different hats all at once but also the power to make choices, including defining bureaucracy and processes. Senior PM implies a much more limited silo of skills but also limited powers and a need to be able to fit in with existing bureaucracy and processes.