First and foremost, this is your time and you should use it how you see fit.

Here are some random suggestions:

- Solve algorithmic problems on Codewars or HackerRank

- Build an app on Python Anywhere (cloud9.io was a more convenient and versatile remote coding sandbox, but its UX has become much worse after they were acquired by AWS)

- Try to answer some questions on Stack Overflow

- Take a coding course on Codecademy

- Take a ML (or any other) course on Coursera

- Take a language course on Duolingo (you won't be able to do speaking exercises, but you'll still be able to learn)

- Write for your blog (on any platform that you can access - starting a site on your own domain is a good option because it will most likely not be blocked by your filters)

Some of these sites can be blocked on your machine, so choose what is available.