Is it possible to sale wordpress sites through facebook ads? And also does it comply facebook policies?
I don't think that FB approves direct selling. Instead you can use a squeeze page to land the traffic.
Now coming to selling sites. Its not impossible to sell a wordpress site in facebook but its extremely difficult these days as because facebook is lurking with spammers.
As far as I know FB prohibits this type of activity. You will need a separate landing page for this.
Then I will just build a landing page then just to redirect the visitors.