1-2 days is enough to learn the basics, but I doubt you’ll be as nearly as productive as with something you’ve been using for years. Keep in mind that new languages also mean new frameworks, etc, some which take years to actually master, but at least months to get a good handle on them.
Also, from my understanding, Rust is a bit of a paradigm shift.
I only watch what’s in my subscriptions. Now and then I’ll add something new to see if I like it or remove something I don’t enjoy.