Needs clarification. As written, two answers are technically true. Here, it seems you seem to be testing the association of glycogen accummulation specifically in muscle, which is a definining feature of McArdle disease.
However, Pompe disease is also characterized by glycogen accumulation within muscle—however, it's not limited to muscle.
UpToDate writes, "GAA deficiency leads to accumulation of glycogen within the lysosome in all tissues. Muscle biopsy reveals vacuolar myopathy with glycogen storage within lysosomes and free glycogen in the cytoplasm by electron microscopy" - https://www.uptodate.com/contents/lysosomal-acid-alpha-glucosidase-deficiency-pompe-disease-glycogen-storage-disease-ii-acid-maltase-deficiency
Source: Other - https://www.openevidence.com/ask/8fb683e7-cc8f-4141-b89d-1324f5a404b9