Yes normally the Garden Grove is only open for Breakfast on select days (Closed Tuesday - Wednesday).
For Thanksgiving dining I would suggest you call
407-934-1609 directly for Swan, Swan Reserve, and Dolphin dining. The Garden Grove does not normally take reservations for breakfast. So it is not on Disney ADR system or even on
OpenTable.com
Also while the
MDE Dining is not currently working the web version is up and working:
https://disneyworld.disney.go.com/dine-res/availability for other Dining reservations.
Dave.