I don't know the actual statistical percentages, but many left handers starting from scratch without encumbrance of injury choose to learn to play guitar right handed for the reason of a massively wider choice of instrument availability as was. Even today, left hand instrument choice can be severely limiting.

e.g. Yamaha don't make a single left handed model in their Revstar range. Of the Pacifica range, only the 112J (2nd tier segment with ceramic pickups) is available in a left handed version, and up until recently, in only a single colour. No top tier 612VIIs in a lefty. Their acoustic and electric beginner Gigmaker packs are exclusively right handed as are their entry level through about tertiary tier acoustics. It's rough IMO, and I have empathy for lefties, but how it is with market forces. I can see why lefties might decide to learn right handed.

Speaking with those who have taken up the off handed challenge and can now play, they don't report learning off handed impeded them.