What kind of use cases run in an environment where latency isn't important (some kind of batch process?) but don't have more than 4GB of RAM?

Price sensitive ones, or cases where you want the new capability but can't get any new infrastructure.

Not LLMs, but locally running facial and object recognition models on your phone's gallery, to build up a database for face/object search in the gallery app? I'm half-convinced this is how Samsung does it, but I can't really be sure of much, because all the photo AI stuff works weirdly and in unobservable way, probably because of some EU ruling.

(That one is a curious case. I once spent some time trying to figure out why no major photo app seems to support manually tagging faces, which is a mind-dumbingly obvious feature to support, and which was something supported by software a decade or so ago. I couldn't find anything definitive; there's this eerie conspiracy of silence on the topic, that made me doubt my own sanity at times. Eventually, I dug up hints that some EU ruling/regs related to facial recognition led everyone to remove or geolock this feature. Still nothing specific, though.)