I've build BlueRetro [1] an universal Bluetooth controller adapter for nearly all pre-USB gaming console. I've been working on it for the last three years.
I entertained the idea to make and sell the hardware myself. But in the end I learned that's it's not something I'm interested to get into. What I really like is working on the software.
In the end this pivoted into a more community driven project where multiple makers are selling various variations of the HW and giving me a cut of their profit to support the SW development.
Recently I even got a Chinese company, notorious for selling "clone" of OSHW projects, to support the SW development as well via GitHub sponsor.
I wrote a retrospective of last 3 years [2].