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I'm completely sympathetic to your concern.

Cramming is a bad habit. My suggestion is to set aside 1-2 hours a day in the morning or evening to build things, do research and improve your skills. Continue this habit once you start your job. This will be plenty of time to keep up.

Of all the things you listed, building real apps is the only thing that will see you really making progress. Everything else is too shallow and it's also hard to stay engaged in it.

Keep in mind that your new job wants you to apply yourself daily using their bread-and-butter technologies more than they want you to understand new technologies. For example, they probably want you to bang out React components or Rails views more than they want you to understand the more esoteric bits of those. As a web developer, consistent work > insight, every time.

Strongly suggest retreating even further from idle Internet use if possible. It is not good for you.