Is there a way I can display one image field if another one does not exist using visibility rules in node template? I can do something like this with a text field, because I can compare it to an empty string, but I can't figure out how to do it with an image field.

Visibility rules supports content:exists, but this only applies to the content the rule applies to, not another field.

Is there a way I can display one image field if another one does not exist?
I would suggest using views to create a block based on the filter criteria where the first image field is empty.