With all due respect, the two situations are not comparable as Haakon is not 6th in line and one of the sons of the future king.
The question, however, that I would ask you as a Canadian is whether the Canadian government would agree to consent to removing Harry and Archie from the line of succession if asked by the British government.
My opinion, as expressed in an earlier post, is that, realistically, the process would have to start with Harry himself making and signing a "Declaration of Renunciation" just as Edward VIII made his Declaration of Abdication. I don't think Harry would do it on his own free will, but he may be asked by his father/brother and the UK government to do so. In that scenario, I think the Commonwealth realms would consider the matter; otherwise, it is not inconceivable that there could be a split between the UK government and the governments of the other realms.
However, for a transnational/shared monarchy, it is a matter not only for the people of Britain, but also for the people of the other realms and we don't know how they feel about it.
The situation in 1936 was actually simpler than it is today. The Statute of Westminster had not been ratified yet in Australia and New Zealand, so they didn't have a say in Edward VIII's abdication. Ireland on the other hand probably saw the abdication as an opportunity to cut down even further on any constitutional role for the King in the Free State. So, only Canada and South Africa had in practice to be brought on board and both eventually supported the abdication.
In a hypothetical renunciation today, not only 15 realms would have to be on board, but in countries like Australia for example, even individual subnational units, e.g. all Australian states, would have to approve it too.