I very much agree. Rust has some good ideas but the more I've tried it and played with it it lacks that restraint you mentioned. Sooo many concepts, so many sub-languages for different parts. Don't get me wrong, I like the memory safety and that is an honorable goal, but I am not even sure I think ownership / uniqueness types are the best solution for that. There are so many other interesting solutions to memory safety that I think needs to be investigated and tried and I am getting a bit upset that Rust people seem so "our way is the only way"-sounding. But maybe that is just me, as I said I like some parts of the language.
Like you I am looking at Zig and a few others. A recent one I that really caught my eye was Austral (which uses linear types which is the more restrained cousin to Rusts ownership for example).
I like C quite a bit for systems programming because it's design is simple, minimalistic, and cohesive - especially given its age. It does not restrict how I design my software. I'm (usually) unsurprised when reviewing the generated assembly. I wish C "successors" would show more restraint. They _usually_ fail on at least one of these points. With that said, I am keeping my eye on Zig, Hare, C3, and a few others.