How can I store a test file in postman?

I want to use Postman to test an operation in my web API that accepts an Excel file.

How can I make a file available in a Postman test?

The file in question is around 10-50kb.

1. One way is to base64-encode it and store it as a variable, I can then use atob to get it back.

2. The second option is to store the file somewhere and use pm.sendRequest to download it (github, public s3 bucket, something else?)

3. The third option is to change my web API to either act as a file-server and vend the test files I need for testing.

I would prefer to just have an option to load the file from disk, but I don't think Postman javascript sandbox has an API to load files.