I have no idea if this guy is any good (I believe the "hardware product" he brought to market was a simple stick-on LED front light for tv remote controls or something like that), but he now consults on exactly this, and his blog/email posts are certainly extremely interesting and plausible:

https://predictabledesigns.com/

tldr: it's a huge jump (like 90%++ of the effort) from even a polished prototype, to a ship-able box, let alone one sitting on a shelf in Walmart etc

disclosure: I merely subscribe to his email newsletter, but I too have some h/w ideas I'd love to make into products.