I don’t know about reading values into HA, but I’ve set up my home assistant to display a graph from google sheets on the states panel, using the camera component and a published graph. It automatically updates and everything!
camera:
- platform: generic
still_image_url: https://docs.google.com/spreadsheets/d/1-sUu4kkJKrAodU_8x2IaiOceCD9Uc8a7jdIDwjf8Uho/pubchart?oid=1527554062&format=image
name: "Some name for your sheet"