Ubuntu Touch uses a compatibility layer in order to be able to use Android Linux kernels and device drivers. AFAIK this compatibility layer is currently only compatible with Android 11 and below, which means it is not possible to port newer devices until this is upgraded.

From the article:

Those are recommended either because the companies (e.g. Volla and Fairphone) are directly involved in the development, or some devices (Google) are supported by maintainers with a good long-term track record.

Unfortunately, there aren't much phones that can run mainline Linux and have all hardware working. Most phones use stripped down Android running in container to use Android drivers to talk to hardware.