NATO allies are expected to standardize their military equipment and processes to some extent, so they can interoperate with each other. This is why there's NATO standard ammunition, and why the US military does a lot of stuff in metric.
One non-dirty-tricks reason to do this would be to give Ukraine ample time to get all that administrative stuff in order.
Canada at least has a "Governor-General" who is appointed by the British monarch.
Edit: like several other commonwealth states, Canada is a completely separate country from the United Kingdom. It just happens, by law, that King Charles III is the king of all of them.