Ok... Instead of replying, you edited your post. No fair...
IMHO, the best option is to set up a Spa Panel as a plug in device for the existing 240V outlet in the garage. This way the building wiring is not altered in any way & does not require an electrician, permit or inspection. (If you alter the building wiring without a permit & inspection and s**t happens, your insurance sends you down to the deep mud pit. No coverage and out of luck.!)
BTW, getting a GFCI breaker for the mains panel or the sub panel could be very expensive ($150 +/- depending) where a Spa Panel will cost about $55 from HomeDepot. Wiring? I drew and have the diagramed plans. If that's the plan, I've made them available many times in many posts before and will do it again here if needed or wanted.
Another BTW: Setting up the Spa Panel allows you to have the GFCI breaker close to your brewery. When something happens that does not look or feel right, hitting the E-Stop is a no brainer. You would just do it. Now if you had to go 2 or 300 feet to reset it? You would never hit the E-Stop unless flames were --- Nevermind... I'm done.
Just do it your way..
P-J