It's not on the roadmap, currently. But if someone wanted to contribute code to make that happen I wouldn't veto it.
If the web site is built properly it should be able to provide a mobile experience that is as good as any app. The big advantages that apps have is that they have direct access to the phone hardware. But there is nothing about PieFed that requires direct access to the phone hardware (3D graphics, sensors, storage, etc) so at the moment my effort is best directed at making the web site's mobile version as good as it can be.
If your phone's browser supports it, you can get a PieFed icon on your phone's app launcher / home screen by using PWA: https://mastodon.nzoss.nz/system/media_attachments/files/111/710/493/644/170/923/original/db8ee991eea352e3.png