You can use CLIP to build a database to search (offline) for keywords like “nude” or “naked”. Specifically, I use clip-anytorch with the ViT-B/16 pertrained model and find the result very good. Just go to pypi and the corespondent GitHub. They have examples and demo for a quick start. It can run on CPU, too, albeit a bit slow.
No experience with any of this, but a quick search turns up stuff like https://deepai.org/machine-learning-model/nsfw-detector, which looks affordable and straightforward to implement.
And here's bunch more: https://rapidapi.com/collection/nudity-detection-image-moder...