I'm using a community photo gallery component that doesn't work with Artio SEF or my Joomla SEF. I'd like to exclude those pages from being shortened, but I would have to exclude every new picture detail page that someone adds from the list, right?

This goes the same for regular articles in any generic Section or Category.

Is there actually a way to automatically exclude whole components/sections/categories when new content is added through or to them?

Hello,
it is possible to choose how (and whether) to treat URL on component level.
So you can disable SEF (JoomSEF) for the whole component or choose whether you prefer Joomla core SEF or no SEF for it. This is done in Extension Manager, by clicking the component name and adjusting the way of how URLs should be handled.