ESP32 hangs when booting without wifi

The answer is in the link you provided. Although the OP never returned to share if it worked or not. I suspect it did since he never reported it didn’t (if that makes sense).

  WiFi.begin(ssid, pass);  // Non-blocking if no WiFi available
  Blynk.config(auth);
  Blynk.connect();

and additional connection management as needed, with an example provided here: