iOS & Android App Development

I already have every screen designed and laid out; you can see the full product brief here:
https://docs.google.com/document/d/1orcg2KzdkDi8TtR2Zh1KEvFaR4xBdDoG/edit?usp=sharing&ouid=103211339611281408484&rtpof=true&sd=true

What I now need is the complete build of the app for both iOS and Android, plus a brand-new backend that supports everything in the document. The UI/UX is final, so the job is all about clean implementation, solid architecture and a smooth hand-off.

Key points
– Native-quality experience on both platforms
– Full backend development from scratch (database, APIs, deployment, monitoring)
– Source code and working builds delivered in staged milestones

Please review the brief, propose the tech stack you feel is best, outline your timeline, and break down your pricing by milestone. Let me know if anything in the spec needs clarification; I’m ready to get started as soon as we lock the plan.
Budget: $600