The Blynk library can’t read the data directly from the D1 and D2 pins on your NodeMCU and send it to the app via the Blynk server.
Instead, you need to use the HX711 library to take the weight reading and assign the result to a variable. You can then send the value of this variable to the Blynk server/app.
There are quite a few examples of using the HX711 with Blynk, here is one example…