Edmonton to Kamloops passes through mountains, but not over anything significant. The high point is on 16 on the provincial border, but the climb from Jasper is gentle.
BC 5 is in a broad river valley.
I haven't driven 1 (TCH) east to Salmon Arm, but on the map it looks flat, though settle farmland and lake shores.
97B&A south to Vernon, and 97 to Osoyoos is also settled orchards and lake shore. Some of that is busy urban freeway.
All other ways out of Osoyoos involves some grades. Crowsnest climbs steeply out of Osoyoos, and has several more grades. But the last pass, Crowsnest iself, on the provincial border is as gentle as the 16 one.
TCH east of Revelstoke has a couple of good climbs, though it is a busy, and largely divided highway (Rogers Pass and Kicking Horse).
