flutter app development

Hi I attached the raw app specs.
Honestly, give me a breakdown of total cost and time this app could take to have at least the main features done and if you recommend to work with 1 or 2 more people to complete this project.

App #248
Filters app for android and iphone from artists pictures (App248).
I need another app with these specs for now.

LOGIN:
• Email and password fields.
• User can login with current user name and password related in another website hosted in AWS. So a Database is already in place for an ecommerce site. We would like to make it easier for clients to share the same login for the app and the site. Maybe creating an API for the website to integrate with the app would be the solution.
• Social login: Twitter, instagram, facebook Api integration.

MAIN FEATURES:
• Client can add a payment method to their account (paypal. Credit card etc)
• User can buy shots that wil be used to pay for the overlay picture of the artist in the selfie.
• Logged client can select an artist or band (bands have many members). Then an artist from that band as a filter for a selfie or picture.
• User take picture multiple temporary shots with the overlay, then select the final picture. Then the shot is reduced from their account.
• User can now save the picture in phone, add filter, stickers or freehand draw on top of the picture with brushes.
• Users can’t take screenshots which are blocked during the app is open or a watermark appear if an screenshot is taken.
• Client can login and manage their account from website. Can manage their profile, add payment system and see saved pictures. Can’t add more pictures.
• Can purchase shots, filters and stickers from website and will be reflected in the app in their phone.
• Overlay pictures, stickers etc can be added and removed from the app. As needed.
• App wil be hosted on ---------- CONDARY FEATURES:
• Filters
• Stickers
• Wishlist (add artists poses to a list for future purchase)
• Draw on top of the picture with brushes.
• Redeeamable Rewards points.
• Account growth levels according to activity on app (Novice, apprendite, master etc)

Example:
Emyli Marnipe purchase 1 shot. She browses the list of artist in the app.
Pick brad pitt, Brad Pitt have 8 different poses. She picks one and the camera opens automatically for selfie, she can select the back camera too. She resize and place the picture in the screen. She takes some pictures and click (back to delete them) until finds good one. Click next and it gets downloaded to the phone and saved to her account automatically. The paid shot is removed from her account.



For now this is the goal of the app.