Currently you cannot import using the ClickUp mobile app.

You can import using the web, however the web is not mobile friendly (it's awful).

This means you should have a separate computer to import data into ClickUp, which is awkward as you may not have a computer (mobiles rule! 😁) or you simply don't wish to start up the computer to run this specific task.

Since most of the import functionality happens behind the scenes (on the ClickUp servers) it seems trivial to add the import option into the mobile app.