Absent Article 50, surely everything the UK needs to do in the 2 years period would be legal for an EU state, because Greenland managed it? The trick is/was tha

Absent Article 50, surely everything the UK needs to do in the 2 years period would be legal for an EU state, because Greenland managed it? The trick is/was that EU rules (fairly obviously) allow the EU states to negotiate changes to the agreements binding the EU together, including negotiating an exit whereby one of them leaves the EU but retains some access to the internal markets.