Guys I received my passport back. Was a bit anxious that package might encounter customs clearance issue because I didn't include any commercial invoice (read a few posts on the forum where folks were asked to email one to CPC-O). But it turned out not to be a problem at all. So I guess if you properly declared the shipment as "Documents" and followed Fedex instructions, which explicitly said that a commercial invoice was not required for non-commodity items such as docs, then it should be fine.
It was great tracking the process with people in the same boat sharing similar kinds of anxiety of waiting in these threads. If you're waiting, I wish you get your docs back asap
Delivered to CPC-O 7/12/2019
Received by CPC-O 7/16/2019 [got to know this by calling IRCC]
Approved 7/29/2019 [MyCIC account update]
Return tracker activated 8/1/2019