Halo CE now runs on Quest and Android without a PC: the
HaloCE-Quest-VR project has been
published with source code. The author under the nickname moistman42069 released a standalone build of the game. Full-body IK, finger tracking on controllers, multiplayer via native port, and experimental co-op are claimed. This is a community build, not an official release, so bugs are possible. But those who want can download ready-made builds or build the game themselves.