Build me a fastapi or flask app

I would like to build an app to work as a tool for nutritionists. Here is a little user story to help you understand what I am imagining: - As a nutritionist I can create an account on the app - As a nutritionist I can create a house object and assign patients to it - Each patient will have attributes like personal information (like name, email, phone, age, gender, etc), a list of all the meals it regularly have at home (like, for example, monday: breakfest and lunch; tuesday: breakfest, morning snack and dinner; wednesday...), and a mapping of products x meals x quantity (like, for example, {apple: (['breakfest'],150g)}. - As a nutritionist I can invite an patient to become a user of the app and linked to specific house - A patient user would be able to visualize and edit patient attributes of the house it is in, like edit the list of weekly meals that take place at home and the products mapping - As a nutritionist or patient I would be able to see a dashboard with info like all the food products the was bought by that house as well as how each product is segregated between all patients based on the product mapping and meals that take place at home. It would also contain info like the nutrient facts and ingredients of each product - As a patient I would be able to scan the QRCode that comes I all shopping receipts (this is something specific to my country and state) or send the QRCode image by whatsapp to a specific phone number To get the product info the app would use the info extracted from the QRcode. It is a 44 digit key that can be used in a specific public website where consumers can see a table listing all the items of that specific receipt. The app would have to break the recaptcha and scrap this web site to get the info. Each product line on the scrapped table has a barcode. If the barcode has more then 7 digits it would use it to query a database that I have with product info. If it has less then 7 digits it would query a different db, using the product description instead. Based on that I would like to know if u can do it, how long it would take and how much would it cost. Also I would like to use the data collect for other services in the future, like selling products. With that in mind I would like to know if you are open to discuss software architecture. I am not an expert on the subject, but I would like to start with something that can grow and aggregate other services.