Yes, there is a lot of concern in the ROI about how the Irish state would fund everything, especially if it would be necessary to deploy military. Ireland has a minuscule military (neutral, non-NATO etc), and obviously is a much smaller economy than GB. However, there is talk that the EU would support reunification.
> They’re also a bit leery about having the DUP as a political party.
Exactly. As I understand it, the DUP would have a larger influence the the Dail (Irish parliament) of the theoretical reunified Ireland, than they do in Westminster. Since they are a reactionary, conservative party, which doesn't exist in the ROI today, it's certainly a concern.
The attitudes and situation has changed a lot in recent years, especially because of Brexit. Here's a good read:
https://old.reddit.com/r/northernireland/comments/uar1yc/any...