Agree with the OP that it is a dopamine hit to find something that's niche, which also agrees with your sensibility or mental model, or to find the "sweet spot" to use a sport analogy.

For day job I code in high level languages like: javascript/typescript, python, and back in the day: ruby, perl, and php. Never was comfortable in C/C++ but always wanted to get more proficient. And felt like to be honest programmer, I need to know a systems language.

Lately I've been learning Zig https://ziglang.org/ and I'm quite happy with the developer experience, despite it's only at version 0. It's kind of a whole new world I didn't think even possible: C level performance, but with great ergonomics and just basically: it's fun to develop in! Like C, but fun and safe(er).