Please note that a lot of the bonus cards are more appropriately described as "bonus coupons" and are not gift cards. They typically have no cash value, include an expiration date, and may have other terms attached. You should check with the respective restaurants for details if you have any questions. I've listed the expiration dates where I could find them.
Some deals are online only, while others are available at participating locations only so be sure to ask before buying.
Here's a list of restaurant gift card bonuses/freebies available for the 2020 holiday season (I'll update if more come in):