I built my proof-of-concept on my own.
Lessons learned:
- Working on your own rocks because - you can do what you want, when you want to.
- Working on your own sucks because - you do what you want, when you want to.
It isn't a route for the unmotivated. You also lack a feedback loop, so you can't be sure you are producing high quality stuff as there is no local sanity check.