The Arduino 2.0 IDE is very different and installing Teensyduino is a new process. You no longer need to download the Teensyduino, as the Arduino IDE will do that for you. This install process follows a similar process to the ESP32 and ESP8266 boards.

Here are the JSON install strings

TeensyDuino
https://www.pjrc.com/teensy/package_t...


ESP8266
http://arduino.esp8266.com/stable/pac...


ESP32
https://dl.espressif.com/dl/package_e...