To start off, I have been to First Watch many times with and without my family (who eat gluten-free), and every single time the staff has been accommodating and very friendly.
They have plenty of gluten-free breakfast options with foods that are inherently gluten-free (eggs, bacon, fruit, etc.). You can substitute any bread on the menu for gluten-free bread, including the french toast! They always ask if you have a gluten allergy to make sure the kitchen accommodates you.
— Somewhat
— Gluten-free items are marked on the main menu
— Not Much
— Excellent