PC/104 is a known platform and would make a great reliable solar powered waypoint/RF repeater type Payload for instance. Wide PN spacing in the silicon substrate allows for lots of comic rays chipping away at it without much degradation in performance.
Android and Apple off the shelf smartphone platforms are great. And hey, any kid can code an app. But, can they survive on the Moon long enough with such narrow PN channels?
Hardening a standard cell phone circuit board would be key to making them survive for the just under 200 hrs. for this Challenge's extended expectations. Then add in the uncertainty of landing at unknown location, i.e. temp and light conditions, does throw a bit of twist into considering "lightweight" platforms.
Faraday caging, Mu-metal shielding works well for shorter lengths of EMR. How well they will perform for cosmic and the even shorter wavelengths, I know little of for now.