That's the biggest problem I have with Recall. Not that the idea or functionality is bad, but that the probability that the company behind it will abuse it is so large that it's not worth the risk.

If the system worked fully locally, didn't come from Apple/Microsoft/Google/Facebook/etc., and had decent data isolation, I would probably turn it on.

Unfortunately I find that getting basic OCR to work reliably on Linux is a challenge in itself compared to Windows' APIs and quality of OCR results, so I doubt an honest, well-intentioned implementation will make it to Linux.