In Northern Ireland, there is already an agreed path to reunification as set out in the Good Friday Agreement.
That question of the devolved funding settlement is expected to be discussed, alongside other ways of working together in areas such as the economy and energy.
But perhaps the biggest opportunity for the nationalist leaders lies in the political rather than the practical.
Speaking ahead of the meeting, Swinney said: “For the first time ever, Scotland, Wales and Northern Ireland are led by pro-independence first ministers.
“There could be no clearer sign that the status quo is not sustainable – and that Westminster must prepare for a post-UK future.”
O’Neill echoed those sentiments, describing it as a “clear indication that people see that Westminster is not working for the people of the North, Scotland or Wales”.
A photo-op featuring three nationalist first ministers is certainly a very visible reminder of the recent shift in the UK’s political landscape – “good optics” as they say.
And the prospect of the trio of parties signing up to a shared agreement – aimed at putting pressure on Downing Street to plan and prepare for referendums – is a media spectacle, even though it carries no real weight.
The timing of this summit is also a gift for the SNP.
At last week’s PMQs, Andy Burnham seemed to accept a parallel with Northern Ireland that if, and when, support for constitutional change reaches a certain level, a referendum in Scotland could be considered.