Powerapps - Collect data on a drop-down list based on another dropdown list and change to view mode only

Question

I have a SP list (attached you'll find an excel sheet with dummy data) and in my page I need specific data on 4 different boxes as follow:

• Offer number: is a text box autofilled from a gallery and can't be modified manually

• Status offer: is a text box automatically catch the status from gallery and can't be modified manually

• Product code: is a dropdown list that shows the completed list of product related to the offer number and is structured through a 1:n ratio

• Status product: what I need here is a dropdown list that shows by default the status of each product code from the sharepoint list (if I change the product code automatically change to the status of the product selected) but then during the operatioal management of the offer the operator can choose from different status (Open, Won, Lost, Cancelled). If the status is "Open", this element can be modified but if they select the others, the dropdown list must change to only view mode.

I'm not working currently with gallery but I have 4 different text boxes, but I'm totally open to change my mind with the best solution.