Do HPV tests screen for specific strains? I ask because HPV is extremely prevalent but most strains are harmless

All mostly harmless. You've done your homework. True, HPV is "extremely prevalent". But even all type, usually are harmless, not just "most strains". High risk types cause cancer more often than others, but still less often than 1 in a thousand infections. Pap testing in women often incudes HPV, with emphasis on high risk types, but no HPV tests are approved or recommended in men. Not something to be worried about!