Unlike the asshole above, I know they're not sewers but storm drains, because I'm the journalist who discovered people were living in them twenty odd years ago. I'm also a full stack dev, but unfortunately I'm in London now, not Vegas.
I wish I could point you at somebody, but since the bottom dropped out of Tony Hsieh's little bro kingdom downtown, Vegas hasn't had much of a startup tech community. I mean, if you hang around the Arts District and strike up conversations with nerdy people, you might have some luck, but even housed people wouldn't be guaranteed and I couldn't even tell you who to talk to or which startups even exist in Vegas anymore, since I left five years ago.
As far as being homeless goes, you're in a hard town for it, but I'm sure you know that. Catholic Charities is one of the few places you can reach out to, they're just north of downtown near Vegas and Foremaster. If you had a car you could move around between Walmart parking lots. Shelter space is effectively nil.
The Arts District, maybe Commercial Center these days, the UNLV area: those are places I would think you might meet people who can help and sympathize with your situation. Believe me when I say that I understand and I wish you the very best of luck.
You can do this and get out of that situation. I know because I did.
You got this. You will make it. The way that you make the best samurai sword is with heat and pressure from a hammer. This is that part of your life. Do not lose hope in the flames of life's forge. Every blow of life's hammer is forging the future you. On the other side of this you are sharp and ready for battle. Churches may be able to help you. I know it sounds wierd to suggest them, but Christ is a redeemer. You're one generous person away from being back on track. Libraries and coffee shops can be your office for now. Good luck and I'm praying for you.