Just to add up, an old and obsolete atom-based netbook is a super powerful platform for OpenWrt that you may already have lying around. If it's not too old and you tweak the BIOS and configure power management, it will draw not too much electricity. x64/x86 OpenWrt targets work great, you just need to be careful with the WiFi hardware regarding driver compatibility. Consult wikidevi.com and OpenWrt wiki. It may even be possible to use an integrated wifi.

If it's not enough, you can try to run OpenWRT inside a VM/LXD container and use a host OS for the greater good. It's lots of fun!

Thanks for the tip on the dongle.