Chequers was a punt to find a way through them
I think you'd find that the Irish use Euros these days.

Seriously though the EU will not accept any form of
soft border. There has to be some kind of customs check either at the border or somewhere in the import/export chain. Unfortunately neither would be accepted by the Irish on either side of the border, both of which see a refusal as a way of getting big concessions from the UK government. If only we could have cut Northern Ireland adrift a hundred years ago

The Ulster Unionists were a problem then and still are today.