Can you clarify your question? Are you looking for a map of boat landings where you can put your canoe on the water, or routes that you can actually paddle in your canoe?
Landing sites would be the second step and only nice to have. I am interested in the question how far I will get. I know that I can make xy km/h. How far do I get in the river? Osmand wasn't able to route through the river I was looking for, it may work somewhere else. Water level may vary due to weather conditions. This would be a highly specific need. It would be awesome if osmand could fetch the water level but that's somewhat overkill. It doesn't have to navigate around weirs but it may be nice to highlight that there is a weir.