True, text/gemini is not really suitable for UIs. I did write a wiki engine where the editing is done with sed commands and all responses are text/gemini. It works but people used to modern web apps are not going to love the UX.
You can serve other mimetypes over gemini (the protocol). That's useful for some use cases (eg. ansi.hrtk.in serves modem download emulated versions of ANSI art; requires a streaming-capable client).
But all in all, Gemini tries hard to not be an application platform. These exercises in stretching the limits are fun and IIRC have also guided the development of the spec. But the focus of the project is on text-based content.
You can serve other mimetypes over gemini (the protocol). That's useful for some use cases (eg. ansi.hrtk.in serves modem download emulated versions of ANSI art; requires a streaming-capable client).
But all in all, Gemini tries hard to not be an application platform. These exercises in stretching the limits are fun and IIRC have also guided the development of the spec. But the focus of the project is on text-based content.