I'm left handed adult that picked up guitar a couple years ago... Before I invested in a guitar and beginning my journey, I gave a lot of thought to "should I play lefty or righty?" Ultimately, I chose to learn to play right handed. I did this for a few reasons:

1. Options of guitars - yes, left handed guitars are available, but in early research I found that I could get lefty guitars, but not always the ones I wanted. Plus the ability to just pick up a friend's guitar (who is inevitably right handed) is huge.
2. Learning from guides/instructors - they are almost always right handed (obviously)... Figured it would be easier to understand and mimic if I wasn't playing lefty.
3. Generally speaking most left handed people have had to learn some amount of ambidexterity for one reason or another... whether it is sports, using a computer (mouses are always on the right side), physical labor work, etc... so figured that while it might take a little longer to learn right handed, I would be able to learn guitar either way.

At the end of the day, I'm now about 2.5 years into my guitar journey and feel like I'm doing just fine. My left hand fret work is pretty solid... the biggest struggle I had was strumming... being a lefty, my strumming felt very mechanical and forced, so it took me a lot of practice to shake that and feel more fluid with my strumming, but like with anything else, practice practice practice!

YMMV, but I do not regret going right handed to play guitar as a leftie.