DIY Glycolysis

Step One - Oxidation of Glucose

May be Possible but is Undesirable.

Later you will cut your six carbon molecule in two using aldol cleavage. When a monosaccharide is subjected to aldol cleavage you get two monosaccharides. If you oxidise you won't have a monosaccharide anymore and the products of cleavage won't be both monosaccharides either.