I have a '19 GLI in Pure Grey. Wonderful car. I absolutely love it.
Like Bruno said, the VW clear is a bit hard. What kind of polisher will you be using?
In my first go of polishing the car I used Griot's BOSS Correcting Cream and needed to step up to a B&S Uro-Fiber pad to cut down the defects with my ol Harbor Freight polisher. But mine was purchased used and HEAVILY swirled. If you manage to procure a beautiful new GLI and skip the dealer prep, I would say microfiber will not be neccessary.
I just polished the GLI again recently in preparation for a new coating of CQuartz UK + SiC and used Buff and Shine Dark Blue Uro-Tec pads and CarPro Essence with my Makita forced-rotation polisher. That combo was enough to take down the marring of ~15 months of daily driver abuse and plenty of washes.
I would aim for a medium-stiffness pad like the B&S dark blue or a Lake Country Orange flat pad, and use a polish that has some versatility like Sonax Perfect Finish, Griot's Correcting Cream, or 3D One. Because the paint is harder, the stiffer pad and one-step polish will still finish out beautifully. If you plan on coating afterwards, I can certainly recommend Essence and CQUK 3.0 as they are super user friendly and the resulting gloss is wonderful.
Edit: a pic :xyxthumbs: