This pseudo driver does not exist yet, this page collects thoughts on it
The pseudo driver is a driver that allows doing arbitrary mac80211 operations from userspace. Major points are getting frames that mac80211 is transmitting and "receiving" frames into mac80211. Additionally, the hw configuration calls mac80211 does should be passed to userspace and handled there. The userspace tool should also be able to call many of the mac80211 functions.
The interface for the pseudo driver should probably live in debugfs, maybe having one file for frames and one file for control operations/hw conf calls.