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.
I know you're probably scared shitless, because I've literally been exactly where you are - a homeless dev in Vegas. (If you're at a café using the wifi, especially downtown or down Maryland, I've been where you're sitting.) If I were still in town I could offer you more help, but everyone I knew in Vegas tech either moved away or died.
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.