Gemini has had the ability to create files for a while, but it didn’t really work that well, for me at least.
It looks like they’ve updated the feature(s), and you should be able to consistently create downloadable assets with the Gemini app (on the computer, I haven’t tried the mobile app yet).
It works the way you would expect it to. Ask it to create one or more files and tell it the type(s). You could leave it at that, but I recommend adding a little bit more information to get results that you’ll be happy with.
If you ask for local files, then Gemini will run some Python code and then give you files that you can click and download.
If you send files to Google Drive, then it will save them in My Drive by default.
You can request the following file types (for now…) -