Your situation is very similar to mine. I also applied for a study permit extension on October 17, and my previous permit expired at the end of November. I finished my courses in mid-December and am waiting for my new study permit to apply for the PGWP. My application is also still in the background check stage. However, I’m very sure that during this time, you can work normally since you are on implied status. But I’m not sure if you can directly apply for the PGWP. Right now, I’m waiting for my college’s completion letter while also waiting for my new study permit. I’ve already prepared all the other materials for the PGWP application.