I'm venturing a guess that a symbol that may constitute a rallying cry for hardcore Brexiteers is going to be the "Irish Sea border" which is already making its (still subdued) appearance as a practical reality following the implementation of the Withdrawal Agreement.
I can easily imagine impassioned speeches how that setup impinges on UK's sovereignty, as being a surrender to a rule from Brussels... In fact, I don't have to imagine them. For example, former Brexit Party MEP Ben Habib said on Dec 1st:
"I can't see how Boris Johnson unpicks the withdrawal agreement or how he unpicks EU state law applying in Northern Ireland and therefore the United Kingdom."
"I can't see how he will get rid of the Irish Sea border and how he is going to ensure that we stay out of the level playing field, having promised to sign up to it in the political declaration."
And consequently Habib says it will take the UK 25 years to fully regain its sovereignty. In other words, in this vision, (true) Brexit is a long-term project, which includes the dismantling of the Irish Sea border.
So, are there any polls on the level of acceptance of this "Irish Sea border" setup among the UK public?
The DUP was fairly adamant against it last year, but they seem to have softened their stance along the lines of "let's see how it works in practice". In view of that, this question may seem premature, but I'm interested mainly in how many still oppose it as a matter of [sovereignty] principle.