There are a very small number of handguns out there that are truly ambidextrous. For example most of the S&W M&P line has an ambi slide stop, but the magazine release is *reversible*, not ambi (I own two, heavily because at the time I bought my first there were even fewer options for a southpaw).
Note that some firearm manufacturers talk about a firearm being ambi or left-handed if it has *any* of the controls either ambi or reversible.
Being left-handed is also not protected under the ADA, BTW (nor, IMO, should it be).
Sorry, personal pet peeve - I'm a leftie, but my wife is right-handed, so I've spent a lot of time looking for firearms we can both use easily without needing to field-strip them.