I had a chance to handle one of these and this is exactly what I expected from a smart phone, absolutely fantastic and the level of open source on the driver level is elite.
This works great for single and potentially two later boards, the problem is when scale up to 4 layer and beyond boards. For quick turn production level boards I have used https://www.allpcb.com, JLPCB takes a day or so longer than ALLPCB in my experience.
It's helpful to find your first customer. Someone that believes in you and your skills. I'd be more than willing to be your first customer if you could provide some examples of your work.