Build it. Gentoo, Arch, and any other minimalist distro where there’s less userspace fluff out of the box can easily be configured to be incredibly hardened.

Your looking for a desktop distribution that doesn’t really exist out of the box (perhaps Qubes). Android is a mobile OS for a reason and has a different architecture in userspace to accommodate for is threat model and use cases.

Just because desktop distros don’t typically lock down userspace out of the box doesn’t mean it’s not possible.

Edit: Here’s some examples:
Plague Kernel
Hardened Arch Linux
SELinux for MAC
Kernel lockdown
Immutable distro BlendOS
Bubblewrap sandboxing
Firejail sandbox leveraging hardened malloc
Hardened Alpine Linux

I don’t think there’s a distro that goes as hard as mobile except maybe some based on flatpaks rather than package repos of libs and bins. But you can piece your own together based on your requirements and personal threat model.