Search and select a file in the phone

Questions about Thunkable
1

I would like to select a .csv file stored on my phone to process it. Is there a window/object/method to navigate through the files and choose the file that interests the user ?
I have been trying for a week.

2

You could use a free online converter to turn it into a pretty JSON text string. Copy that into a variable. Use it like any other api response.

3

Thanks for your answer but my problem is that I have no data connection in many places where I use my phone. So I can only work locally. But I have the impression that I didn’t explain myself well: my problem is to find and select a file of any kind, for example a .txt file but now I need to find a .csv file. In Visual Basic I would use a window with the command Commondialog1.Showopen, in Thunkable I don’t know which command/object to use.