There's no native connection that writes from Google Sheets into Canvas. The built-in route is Canvas's gradebook import: start from a Canvas gradebook export so the columns match, enter scores in Sheets, download it as CSV, and import it. Canvas previews the changes before applying them. That covers grading done offline in a spreadsheet. For recurring updates, Make or n8n can read rows and write scores through the Canvas API, using an access token for an account allowed to grade in the course. Match students on SIS ID or Canvas user ID, since names aren't unique.