Most of our area is softwood like pine and spruce, but we do have a fair bit of Poplar and some Birch.
Buying bagged chips is pretty expensive and if I could use local grown wood, then I could keep the cost down.
Never heard of Saskatoon wood and rose hips are loaded with citric acid so IDK how good the smoke would be.
Saskatoon wood. Is a member of berry trees also known as Serviceberries. They look a lot like blueberries, with a soft woody pit. Flavor in my opinion, is a cross between a blueberry and prune, with a nice tart finish.
I have seen the trees 25 feet tall, 4" to 6" bases. It would in texture and hardness be similar to alder. Never used it for smoking.
I burn a lot of different local woods in my outdoor wood fired boiler to heat my house, so I get exposed to lots of smoke. Poplar (quaking and bigtooth aspen) stinks and balsam poplar stinks even worse. White birch bark burns my eyes. Birch with no bark doesn't burn my eyes and I've heard that it's good for smoking, although I've never tried it. I would definitely try it before poplar. If you cut green birch for seasoning and don't plan to split it green, you might want to score the bark vertically, deep enough to expose light wood. This causes the bark to slough off sooner and helps keep the hardwood from getting punky.