There are some that you can find posted on the community forum. Basically, as far as I remember (for the C5 and C7):
1 GB RAM
8 GB eMMC
S905X processor, which is a quad-core ARM A53 processor
I think the C4 has a S905W processor
https://community.hubitat.com/t/faq-frequently-asked-questions-technical-questions/118
