Here are some pics I took a while back of a test piece, single-wall cube with no infill, before (right) and after (left) drying PETG:
and again without flash:
As you can see, the undried filament produced significant cosmetic problems (albeit only visible with right lighting and camera angle). Whether these matter for your application, or whether they correspond to structural problems, I’m not sure. My experience with PETG has been that I don’t hit serious problems that compromise the print from wet filament (like the runaway stringing you’ll get with wet TPU), but that drying is still worthwhile.
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