The interest of the Brexiteers is the same as the interest of all the people n the UK and all the UK counties. It is to allow us to govern our own Union once more, and return the freedom to control our own trade and borders. No self-respecting nation would settle for less. Implying it is not in everyone's interest is simply propaganda.
I've explained a number of times here how one can have an open border between the North and South of the Island of Ireland without either Irish unity or membership of the customs union and single market. I suspect others may well have also.
a) The EU could opt to act like decent human beings and be the 'force for peace' they always claim to be but don't seem to act, and allow the border as an exception to their fortress wall.
Or b) Southern Ireland could tell the EU that they are not going to have a hard border just to satisfy unreasonable EU demands, and, like other EU members, will have something they don't obey.
Or c) Southern Ireland could decide maintaining peace is more valuable that being a small province in a federal EU block, and opt to leave also, and become a proud self-governing nation once more.
And I suspect there are probably a multitude of other options too.
No one is being ignored and the unfounded suggestion that they are is offensive; but it is my suspicion is that that may well have been your intent.