Jekyll: How to use automatic SASS migrator?

I get a lot of deprecation warnings on my jekyll sites.

I have found out this article, that shows automataed migration:

Automatic Migration

You can use the Sass migrator to automatically update your stylesheets to use the module system.

$ npm install -g sass-migrator
$ sass-migrator module --migrate-deps your-entrypoint.scss

If you want to migrate away from global built-in functions, but aren’t yet ready to fully migrate your @import rules, you can pass the --built-in-only flag to migrate the functions while leaving @import rules as-is.

But my sites has a lot of SASS files in _sass which are used in SASS files in assets. When I run

sass-migrator module --migrate-deps assets/css/index.sass

I get this error:

Error: Could not find Sass file at 'main'.
  ╷
4 │ @import main, font, basic, layout, highlight, classes
  │         ^^^^
  ╵
  assets/css/index.sass 4:9  root stylesheet
Migration failed!

All main.sass is in _sass.

How can I use automatic migration tool on jekyll blog? How do I provide context of _sass directory?

Thank you for help