PSA: You can't delete photos uploaded to Lemmy. So don't (accidentally) upload a nude
(tech.michaelaltfield.net)
You can configure the maximum size of image you will federate. You could set it to essentially 0 and you will store like no images. Downside is you will have to fetch images from other instances, whose servers may not be close to you.
For reference, Feddit.dk has a 5MB image limit. My storage is only about ~60 GB