I want to integrate my android studio app with paypal restapi using django server

Follow the PayPal Checkout integration guide and make 2 django routes on your server, one for 'Create Order' and one for 'Capture Order'. You can use the Checkout-Python-SDK for the routes' API calls to PayPal, or your own HTTPS implementation of first getting an access token and then doing the call. Both of these routes should return only JSON data (no HTML or text). Inside the 2nd route, when the capture API is successful you should verify the amount was correct and store its resulting payment details in your database (particularly purchase_units[0].payments.captures[0].id, which is the PayPal transaction ID) and perform any necessary business logic (such as sending confirmation emails or reserving product) immediately before forwarding your return JSON. In the event of an error forward the JSON details of it as well, since the frontend should handle such cases.

Pair those 2 routes with the Native Checkout SDK on the Android side.