I should have said "Much more expensive though compared to something like an ESP32 or RPi Pico". You can get something like an ESP32 Wemos D1 Mini on Ali for $4 to $5 USD, and besides solid performance and I/O, you get integrated WiFi and Bluetooth. Not to mention a community that is likely substantially larger than that built up around the Teensy.
$24 for a Teensy 4.0 over at Sparkfun. That seems reasonable to me.
I do miss the older Teensy 3's and 2's.