We're building a smart camera and one of our competitors is using a depth sensor we're interested in using. If we open up the product, is it common to be able to see manufacturer information for specific parts like sensors?
Warning: I know nothing about depth sensors in cameras.
With that caveat out of the way, it really depends on who your "competition" is. I know that designing and building systems takes way more effort than you (unless you did the work) can imagine. Having said that, if your competitor has a massive research and development department, and they do massive volume (enough to justify making their own IC chips), then even a single proprietary IC can really mess up your hopes of copying a part of their design. Having said this, I would think that if you are a true competitor, simply looking at how they achieved their objective should give you enough information to achieve your objective. If they are a large volume manufacturer, they will have proprietary IC chips, but they will also have common off-the-shelf ICs. If you are capable of achieving the task on your own (your team has the skills), then having a "look see" will allow you an advantaged position to consider the pro's and con's and go your own way. However if you are looking to simply copy everything chip for chip... then I would avoid refering to anyone who already created a product as "your competition".
If your competition is someone who does not have a massive budget or massive volume, then for sure, they are using off the shelf IC chips; and opening their product will allow you to see the part numbers they are using, and you can have a really good idea how to achieve your task.
My advice is: if you can't do it on your own, you probably won't be able to copy someone else's design. It usually takes a lot of skill to reverse engineer products. If you have the skill to reverse engineer products, you have the skill to build it on your own and you wouldn't be asking this question. If all you need is a part number, then this is not the place to find it.
Sorry if I sound feisty... I am only trying to save you a ton of effort. I have built systems before, and it's a lot of work. If you have no clue how to do something, looking at someone else's design won't save you....