Yes, you can use Processing on Chromebooks that support Linux on ChromeOS. Most Chromebooks released after 2019, and some earlier models, allow this. Follow this video tutorial for instructions on how to install Processing on your Chromebook.
To check if your Chromebook supports Linux, visit ChromeOS Systems Supporting Linux.
If you’re using a Chromebook from a school or workplace, Linux may be disabled. In that case, ask your administrator for help.
If you can’t install Processing, you can still code Processing or p5.js projects online. See Use Processing in your browser.