Granted, it is a stretch and not near the features of Claude (no code etc), but at least Proton's Lumo [0] is very privacy oriented.

I have to admit, I've used it a bit over the last days and still reactivated my Claude pro subscription today so... Let's say it's ok for casual stuff? Also useful for casual coding questions. So if you care about it, it's an option.

[0] https://lumo.proton.me/