I wouldn’t even say that. Even if they had a truly unique LLM that ran partially locally with a custom co-processor, Android might still have been a good choice. It’s just hard to beat an open source base that’s already compatible with most mobile hardware, and relatively easy to find Devs for.
It sounds like you don’t necessarily like the idea of using a container (I tend to use podman, but most guides are for docker, so that’d probably be easier for you). From my experience, containerising things actually makes things a lot easier, especially in the long run, and getting started is a lot easier than it seems. You can probably find a ready-made guide to set up a plex or jellyfin container on Debian.