Lmao no he did not. You can vibe code something that’s vaguely Saleforce shaped, but you’ll never duplicate their PaaS, AppExchange, multi-tenant architecture (good fucking luck with that one), runtime enforcement, Apex - I could go on and on and on.
It’s takes very little technical understanding to know it’s not possible. Otherwise, it would’ve been done my now by people a lot smarter than your friend (no offense to your friend).