I think your main problem is that you’ve chosen the wrong hardware with the Pi.
Blynk’s ideal hardware platform is probably the ESP8266 based NodeMCU or the ESP32, and the best programming language for these boards is C++
These boards cost bust a few Dollars/Euros/Pounds each and you don’t have to mess around with operating systems and cope with long boot times the same way you do with the Pi. They obviously have much less processing power, memory and storage than the Pi, but are perfect for having a few sensors attached to them, connecting to WiFi and pushing data to the Blynk app.
Because most Blynk users use this type of hardware there are lots of ready-made examples in the Sketch Builder and many more in the forum topics. Even if you can’t find examples in these locations, there are a great many forum users who can easily point you in the right direction to get your code working. Very few forum users use NodeJS, so there is a much smaller pool of examples and experience to help out.
Blynk is an extremely powerful, flexible and affordable way of achieving the sort of results that you seem to be looking for, and it’s worth sticking with it - but with the right hardware.
Take a read of this topic if you want more info about hardware choices…
Pete.