Catalysis of the reactions: (1) glycine + H2O + O2 = glyoxylate + NH3 + hydrogen peroxide; (2) D-alanine + H2O + O2 = pyruvate + NH3 + hydrogen peroxide; (3) sarcosine + H2O + O2 = glyoxylate + methylamine + hydrogen peroxide; (4) N-ethylglycine + H2O + O2 = glyoxylate + ethylamine + hydrogen peroxide.