A chroot(2) is not a virtual machine, docker, or jail. It merely defines a point in the directory structure as new root directory "/" for a process and its children. As I noted in
your other thread, this does not hide any process metadata.
Obviously, if there is no /bin/ps utility in the chroot directory structure, epiphany cannot run the ps(1) utility directly. But the C library must be included in your chroot() structure, and the C library includes the complete set of kvm(3) functions used by ps() to obtain process metadata. These functions are available to epiphany, or anything epiphany executes as a child process.