Run a lime wedge around half the rim of a highball glass and press into kosher salt to create a half-salted rim. Fill the glass with fresh ice and set aside.
Add the smoky NA agave spirit, fresh grapefruit juice, and agave syrup to a cocktail shaker filled with ice.
Shake briefly for 8–10 seconds, just enough to chill and combine.
Strain into the prepared highball glass over the fresh ice.
Top with soda water and stir once gently with a bar spoon to integrate.
Garnish with a grapefruit wedge or wheel on the rim.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Baja Breeze.