Intent chose file - How to set type as a .keystore?

Question

I'm trying to select a file using the Intent .ACTION_GET_CONTENT

Intent chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
chooseFile.setType("*/*");
chooseFile = Intent.createChooser(chooseFile, "Select keystore");
startActivityForResult(chooseFile, 1001);

This displays all files to select from.

With this SO answer:

What are the possible intent types for intent.setType(type)?

It displays a list of file types that I can set for the Intent, however I can't find an option for selecting only a .keystore file (for a crypto wallet).

How would I add that type as the intent?