Look within yourself and see what is of most value to you that is doable during a commute. Books that you consciously picked? Other resources to browse that can support your growth and help you discover your creativity, how to create more value, or just be able to exist in fulfillment? For this you must honor your own inner knowing; there is an inner intelligence within that guides us towards our highest good.
You don’t even have to do something. You can learn to be. You can study resources about meditation to educate yourself, practice to learn how to be meditative and then you can be meditative during commutes. You can use the time to get more and more awakened to your true nature. This is a very productive action because your evolved understanding will then reflect to your whole life. I would like to recommend an excellent accurate resource for this to save you some time.