To export all of your Squid notes as a PDF:

From the main screen in Squid, long tap on the screen or click the trackpad and hold on each note until all are selected.

Once all notes are selected, choose Export --> PDF --> Save to Files.

Click the "3 Lines/Hamburger" Menu at the top left to browse to your Downloads folder then tap the blue "SELECT" button on the bottom right.

Next you will need to back up the newly exported PDF files to your Google Drive.

Click on the Files App.  It is best to create a new folder to keep all of your notes together.  Click the "3 Dots" menu on the top right to select "New Folder" or press Ctrl+E to create a new folder.  Then name the folder.  Drag your PDF files into the new folder.

Drag the new folder into your Google Drive.