Cross-Platform Submission+Store App (Milestone Tracking)

Hey, I hope you're doing well.
I am currently in the market for a long-term developer to help work on my latest app. This is to be a cross-platform (iOS, Android, and Web - so likely something like Flutter would work unless you think otherwise) that leverages Shopify, or Superwall-like intergrations as well as serves as a content-upload (images/video's/text etc.).
I can't give full details on the app - however the core features are this.

Core Features (MVP)
This MVP includes:
* User Accounts & Profiles
* Secure sign-up/login
* User profile with avatar, bio, basic statistics
* Privacy options for what is visible publicly

Experience / Milestone Submission
* Browse a structured set of milestones (as well as 'Custom' ones that are user defined).
* Submit completion via photo/video + short description
* Internal review/moderation workflow
* Status states: submitted → pending → approved/rejected/More Info Requested
* 'Button' for 'purchase'. (More details to follow).

Moderation Dashboard (Web Admin)
* View pending submissions
* Approve/reject with notes
* Tools for content removal, user management, escalation

User Profile Display
* Approved milestones visible on profile
* Visual gallery layout
* Users can highlight featured experiences

Social Layer (Basic)
* Follow/unfollow
* Activity feed showing approved experiences from connections

This would be built with the intent to run in AWS; but happy again to have reccomendations thrown at me.
Communication is key and absolute number 1 for me, so please only send an offer if you are 100% sure you can commit to fast(ish) and effective responses. This is a long-term venture for us, the MVP is a starting point.