I found a really nice portable router to use, but seems its not Openwrt supported. I think it wont be so hard to get it works with Openwrt since older version are:
Feature wise the device isn't particularly interesting (flash/ RAM sizes aren't listed, but the FCC images suggest even lower values than for the archer c5-v4), so I wouldn't expect anyone to jump and do the porting for you.
Might be a bit late to the game, but just got this same router. After some buggering, RAVPower agreed to send me the GPL-covered source codes, but overshot things a bit, and I've gotten their whole development environment (incl. proprietary code, basically their whole toolkit needed to build a firmware).
The RP-WD009 is an MT7628 device by the looks of it, wit a 16MB flash chip and 16 or 32MB RAM (I've seen both configurations floating around).
The software is horrendous - using an ancient version of the Linux kernel (2.6.21...), old U-Boot, and old everything. Security is bad (e.g., IPv6 addresses are assigned, but no IPv6 firewall rules, or routing), and overall the software is bad.
The dump is here, anyone feel free to grab it and possibly add OpenWRT support.