RPI is good in terms of the ecosystem and software packages more like Apple, modified from Linux something is the close source. The downside of the compute module is the bulky unreliable connector, form of factor. Arducam's SOM3 seems like an alternate solution to CM3, Keeping the minimum magic parts from RPI, and allows you to maximize your design capabilities. It also simplifies the design as well (2 layers PCB). Unfortunately, it looks like they have a problem getting it into mass production, and you have to contact them for such customization services. And they minified the first-gen RPi too.