[hwntw]

I'd say it's worth learning new languages even purely for the sake and love of learning! That goes to both Rust and Zig, Rust is arguably more intellectually interesting, whereas with Zig you'll probably be writing useable hobby projects much quicker (I decided to tackle learning Zig and reading Crafting Interpreters simultaneously, transliterating the code in the book as I went along).

Zig will be much easier to learn than Rust, but it's worth noting that it's syntactically very unstable between releases (there were some huge changes between 0.15.2 and 0.16 to anything involving IO).

It's really hard to predict what you'll actually use professionally in the future or what's going to be popular in ten years, but some of the greatest value comes from just learning a huge variety of topics.

I'm a firm believer in prioritising enjoyment over utility, and I've always found that utility has flowed backwards from the enjoyment. And even if it doesn't, you've had a good time and found yourself richer for it!