Hello,
I've experience in the development of kernel modules and applications in user-space for OpenWRT firmwares. Currently, I own a TL-WR741N, Arch MIPS-24KC, CPU AR7240 where I can do tests, also I have several lab (Arch x86 - VM) I'll can unit tests there.
Also I worked with the firmwares DD-WRT, Tomato and library uClib - uClib-ng (lib used by D-Link, TP-Link and other brands)
King regards.