Finally, somethin’ I know about, gettin’ stuck on rocks- I consider myself an expert, heck I even like it. I get can stuck in canoes, rafts, kayaks. Principles are the same. I’ll take another crack at it- I’m sure the op is long gone by now.
Avoidance- 1) learn to read water and spot pillows. 2)in tandem canoes a bow paddler can make last minute draws and prys to avoid obstruction 3) get your weight shifted toward the object and sink the boat slightly toward the object before hitting it - easier done in kayaks and rafts (high siding) but still very possible for canoes. By weighting the boat before you hit pillow or a rock you are much more likely to bounce off. 4) boof it- a bit risky but basically power over it and time your stokes so you can pull yourself off with a strong forward or draw stroke, boat is likely to spin out of control if the rock is uneven.
Getting unstuck- 1}let the boat spin, in fact encourage by aggresively prying or drawing from the stern. 2} bow paddle can push off with the paddle on the rock you’re stuck on while stern executes the draws and pry strokes3) have the bow paddler crawl back onto the gear in the middle of the boat or even all the way back to the stern (unweight the boat) while stern paddler works to get boat off. This can get pretty comical. 3) climb out of the boat and thus unweight it