No reason to be suspicious any more than any other equipment you'd buy, well unless you're not also worried about Chinese backdoors on equipment manufacturers or other backdoors from other countries. Much rather trust the US obviously. (I'm not open to debate about this though others maybe be). Plus it looks like these would be built for the US military/government so backdoors would make sense and wouldn't be worried about aside from the general security concerns always espoused. But you're competing with crappy Dell laptops and stuff so the bar is already as low as it possible gets there.
Open hardware is great but someone has to build it and it has to be better. Most of the time it's way worse. I'm a little unsure about what these Zerotrust architecture claims are going to turn out to be:
Restored computer sovereignty begins with local supply chains of trusted domestic and allied partners, and extends to Zero Trust architecture.