You can easily generate Google Sheets PDF links via Google Drive to share them as PDF files. There's no need to convert them manually. See the instructions here.

If you’re using a Mac, the process of creating a digital signature on a PDF document is easy. You can create a digital signature by using the built-in Preview app.

If you select multiple files and then Ctrl+click on the selection, you can pick Quick Actions and Create PDF to do just that (most common file types are supported).

To properly sign a PDF on your Android phone or tablet, you'll need to download an app from the Google Play Store.