The point of CSAM scanners is not to protect children, but to circumvent due process by expanding warrantless surveillance. That is antithetical to FOSS.

So, in a word, no.

There Is a tool that someone built directly to scan images uploaded to lemmy for CSAM.

It is really quite clever. The image is put through a ML/AI model, which describes it (Imange to text), then the text is reviewed against a set of rules to see if it has the hallmarks of CSAM. If it does, it is deleted.

This is fully self hosted.

What I like is that it avoids the trauma of a person having to see those sort of things

SCAM or CSAM?

The justifications for closed source scanners are slim, even knowing how a scanner works it would be difficult for CSAM to be altered to completely avoid detection and those gaps could quickly be closed.

We need an open source scanner that can be integrated safely and with trust into FOSS.

This will only happen with government permission as anyone developing this without permission obviously opens themselves up to legal action.

The FOSS community needs to get Governments on side with this but I don’t know where lobbying would be best started. Potentially the EU would be most receptive to this approach?

Don't see why not. You can download a database of hashes and compare that locally. Granted, those hashes aren't "free", but that's due to the legal status of such material. The principle itself - comparing hashes - can be foss.

Yea people can look into the algorithms to see how they work and circumvent etc., but that's no different than with... Anything else. If someone is motivated enough to distribute the material, they'll make their own network. Foss doesn't make any difference here.