Actually better than free. If you've never used Google Express before, you can get a Google Home Mini for $19 (normally $49), and get a free $25 Walmart credit (essentially getting paid $6 to get a Google Home). Just use this link:
https://express.google.com/invite/XNE55N4PC
Using that link will knock the price down from the already discounted $29, to $19. Shipping is free. Then when you receive your Google Home and set it up, you'll find the $25 credit in the "Offers" section of your Google Home app.
Note, the last time they offered this deal it sold out within a few days. They just got restocked, but I wouldn't wait too long.