To add to Ziggy's post - many on the DUP not wanting to be in Government with Sein Fein................when Sein Fein are the largest party in that Government. These particular DUP members seems to be OK with no NI Government.
The difference from pre EU Refendum Vote days - with free movement of goods between the Single Market Zone and Great Britain, that is proposed in the Green Channel - is that then it was only granted because GB was in the EU. Now its likely to happen with GB outside of the EU.
I hope eventually the UK government and the EU agree to Single Market membership, both sides seem to be moving together a little more. I can understand that the EU as instituition felt badly snubbed in 2020, but what we are finding out is that the current arrangement doesn't help some EU businesses access the 67m population in the UK market on their doorstep that they were selling a lot to (example Dutch Flower growers) as well as vice versa.