I would think that Ellison being a congressmen and the DNC chairmen makes him pretty prominent. Besides, we have seen that Democrats, as Hillary has said, like to have "Two positions", a public and private one. If it weren't that they would be destroyed at the polls, more be open about it.
While libertarians and conservatives do share many of the same policies, I would not put them together on the open border issue.
I have also found that there is a difference between small "L" libertarians and the Libertarian Party platform.
As far as a wall, I think one is absolutely needed. In September 2018 there were 41,486 apprehensions made at the border and DHS admits it only catches about half of those crossing. So no, what we have today is insufficient.
https://www.cbp.gov/newsroom/stats/sw-border-migration