Provide something like one or more "folders" to show per competitor (e.g. "mobile screenshots") and when clicking on them, open a modalbox and the user is able to easily click / swipe through them (and maybe also download them)
|Release time frame|
This is possible today. You can create a "Note" custom field where you can attach any screenshots or files. When clicking on this, it would then show the screenshots in the modal for you to click through or download.