Is it against market place rules to incorporate royalty free stock photos into our marketplace assets? Some examples might be, security camera feeds displayed on an ingame monitor, street advertisements, ect
It is not if it doesn’t violate the license for those photos.
There’re many Royalty free licenses, and most of them prohibit reselling.
They also may require you to distribute a license along with the assets or give a credit to the author.
Also, read the part 15 of the submission guidelines:
Street ads may be against 15.3.