I only have old hardware at home. How viable is to practice this stuff on my own projects (and I'd like to touch JS as much as possible, despite everyone being on python)
You don’t need your own hardware. You can use Google Colab for free.
Most of the action happens in python. That being said, there’s a library called Tensorflow JS. It has some pre-trained models you can use off the shelf and run from your browser. Things like face detection and sentiment analysis.