Believe it or not, this is a few years old at this point.
The ATSAMA5D27 from Microchip is the main element at play here, allowing anyone to create mini-Linux computers with relatively low efforts. The SiP means that DDR2 and CPU are married together at the factory, and traditionally this is the hardest part of PCB design.
Since the “hardest job” is done already, a relative beginner could lay out an ATSAMA5D27-based computer. HaneSOM went the other direction: they made the job much much harder by trying to fit everything within 20mm x 20mm space. (by taking advantage of the DDR2 internal layout, there’s no need to “waste space” on that, and therefore pack everything as tightly together as possible).
I know that Rasp. Pi is more popular these days, but I think some people need a custom computer that they solder onto the rest of their design. RP4 has space and power disadvantages over a package like this ATSAMA5D27.