None, it's not supported - the whole SOC powering it isn't (at this point, there's no development for it known either) - and yes, as OldNavyGuy mentioned, the wireless is a no-go area as well. Even if the SOC would be supported, someone still would have to port OpenWrt support for this specific device individually.
Is still the valid answer.
What makes you believe that to be true - and not a typo between '6' and '7'?
Until yesterday I hadn't heard of Lantiq, so thank you for sharing that.
The probability only had to be high enough to make it worth asking the question and that was barely sufficient. Also, while we certainly don't need a thread for every device which isn't supported, given that it appears to have gone unmentioned here, I suspected I might not be the only one looking at that refurbished offer and wondering.