The best bet is probably a pixel phone with GrapheneOS. (Do note, that copperhead os is a scam and is not to be used)
Gnu/linux phones have nonexistent security, other than being niche (so security by obscurity at most). And also, they are not yet usable as a daily driver for me personally, at least.
Whether or not I am allowed to check that my entrance has no locks whatsoever doesn’t make it harder to open it. And the reverse, even if I don’t know the details of the lock in my door, it will not let others pass through.
What if I have a locksmith verify it for me? Like Apple and Android have been checked by several security researchers and while they absolutely have holes, there is are at least gates that can have them. Sandboxing is the bare minimum an OS should do if it wants to have third party applications installed.
Basically Micay is a legitimate security researcher who created the project and it was later hijacked by the company funding some of it. That company since then try to badmouth Micay at any place they find and is doing shady things on top of the still open source code base. Micay was so professional to destroy the verification key at the time of the forking.
Gnu/linux phones have nonexistent security, other than being niche (so security by obscurity at most). And also, they are not yet usable as a daily driver for me personally, at least.