Just to add in the EU SM issue at the border:
https://www.bbc.co.uk/news/uk-politics-47652280
To protect people's health, some plant and animal products that come into Northern Ireland from outside the EU, via Ireland, will still need to be checked. The UK government has said these checks will not happen at the border itself, but it has not specified exactly where they will take place.
It remains unclear what will happen to goods travelling from Northern Ireland to Ireland. Under EU rules, checks would normally be required at the point certain goods enter the EU single market.
The Irish government says it is securing additional space, and has recruited more customs and agriculture staff to allow for a "significant increase in checks and procedures".
How different is that to what is being suggested as a deal now?
It seems now it will be more about declaration? If agree to keep standards they won't care unless it has been imported before and then exported into the SM which is prevented by an agreement to standards at a compliance level? This was always possible if companies are mandated to follow it.