I had found and looked into your openwrt post and was not able to install or detect. I will try again on weekend.
wifi dongle I am using is AR9271 bought from Amazon
https://www.amazon.com/150Mbps-High-Gain-Adapter-External-TL-WN722N/dp/B01GRK34NG/ref=sr_1_3?ie=UTF8&qid=1468944950&sr=8-3&keywords=ar9271
It is very generic part # printed on is PW-DN4210D , did not even come with any documentation not a single page but windows will find it and works.
ebay has same chipset for cheaper they should also work.