It is really hard to say where the majority of the components come from. Take for example the NXP i.MX 8M Quad. It was designed by an engineering team located in Austin, Texas and we know that they used Synopsys’s proprietary DDR timing code, so Synopsys probably provided the EDA software to design the chip, and most of Synopsys’s employees are located in California. However, NXP is headquartered in Eindhoven, Netherlands and the chip was fabbed by Samsung in South Korea, so where do you say that the chip comes from? Probably the majority of the people who worked on the chip are located in the US, but most people would say that the chip comes from South Korea, since that is where it was fabbed, but it may have been packaged by ASE, a Taiwanese-based company.
Roughly 80% of the world’s foundries (i.e. outsourced silicon fabbing) are located in Taiwan and S. Korea, but fabbing chips is a highly automated process which doesn’t employ that many people, so it seems like a strange way to count where something is from.
From a security perspective, where the chip was fabbed probably makes no difference. If there is a backdoor in a chip, it was probably inserted by one of the chip designers. If there is an implanted spy chip in a device, it might be placed between the layers of the PCB, or added during PCB assembly when components are placed on the board or intercepted during shipping. The fact that Purism has the boards made in the US, does the board assembly in its own facility in Carlsbad, California and does the final assembly and shipping from that same facility gives it a claim to security that almost no other company can makes (except Bittium in Finland).
Frankly, I think the fear about inserted spy chips in the Chinese-assembled Librem 5 is a red herring for reasons that I have explained before, but I think the fact that any electronics company should decide to in-source its own manufacturing is something to celebrate. I also trust that people working in Carlsbad, California have better labor rights, workplace regulation, environmental standards and better pay than factory workers in the region around Shenzhen, China.