Sunsong bought out one of the OEM suppliers in Ohio which became Sunsong USA, so you will see their name printed on AC Delco parts. But just because their USA manufacturing is rebranded, doesn't necessarily mean they are the same part.
For their China manufactured parts, their hose and crimps are pretty good. Their challenge seems to be in the fit accuracy and the inclusion of the proper brackets and spacing. It is hit or miss depending on the application. It really does beg the question why they can sell rear brake caliper lines for less than $10 on rock auto while the GM lines are $50.
My only experience with them is for power steering on a Toyota and they were the only option at the time for aftermarket from rockauto. The quality seemed good, but the bracket spacing was not and really a challenge to fit on the application.
For my recent PPV upgrade, I used GM OEM brake lines on the front and didn't consider anything else. It still looks to me that the GM OEM is less than 2x the Sunsong on the front, but the price difference on the rear raises my attention.