The package is installed on my Fedora 38 VM, created two days ago in gnome-boxes (minimal changes, I only removed gnome-software, updated and changed some Gnome settings):
$ dnf list installed | grep ostree
ostree.x86_64 2023.1-2.fc38 @anaconda
ostree-libs.x86_64 2023.1-2.fc38 @anaconda