You can probably just use VueTorrent or qBitController android app for headless mode.

VueTorrent is a web client.

I currently use the official Web UI in an isolated Chromium instance and made an automatic log in page so that I don't have to type in the password every single time I open it.

I add torrents to the qBittorrent instance using a Firefox addon. It's all a bit jank.

I started some work to make my own qBittorrent client for desktop; I don't care about mobile that much.