Catalyzes the coenzyme F420-dependent oxidation of glucose 6-phosphate (G6P) to 6-phosphogluconolactone. D-glucose 6-phosphate + H(+) + oxidized coenzyme F420-(gamma-L-Glu)(n) = 6-phospho-D-glucono-1,5-lactone + reduced coenzyme F420-(gamma-L-Glu)(n) Homodimer. Belongs to the F420-dependent glucose-6-phosphate dehydrogenase family.