That's not correct. But agree that it's tricky to maintain both and make it clear at border which of these two is your primary residence.I had heard you cannot have the US Green card and Canadian PR simultaneously ; e.g., at the border if they see you have both you have to surrender one ...
Maybe read here about keeping a green card if primary residence moves https://www.uscis.gov/green-card/after-green-card-granted/maintaining-permanent-residence
Being a permanent resident and a tax resident are different things. You can be PR and not tax resident, and tax resident but not PR.This is interesting .. a converse question ... if a Canadian PR declares themselves as a non-resident on their Canadian taxes for a year or two, do they get into trouble in Canada? I assumed if you met the physical residence requirement, that was sufficient .. so one could be non-resident for a bit. It seems for US green cards, this is not the case?
Having a US green card may lead to non-routine processing of your Canadian citizenship application or at least at one time it might as it was thought that meeting the requirements to maintain US PR status may conflict with requirements for Canadian citizenship. But maybe it doesn't anymore, its hard to keep track.
What do you mean by "landing Interview"? Do you mean the process of landing as a PR at the port of entry? To the best of my recollection having a US green card really isn't relevant at that point, although it may be an issue down the road for citizenship, but not an issue that cant be overcome depending on the facts.I am going to get the GC soon, and on the other hand I am eligible for citizenship application right now,,, so I can have both "theoretically" unless something strange such as a conflict of intent to reside or something similar is going to affect me...
at the moment I am more worried about my wife's PR landing interview. is it really important (to be safe/ not to raise red flags for the interviewer) to have her landing interview before we get the GC or actually they don't care about GC?