Ada definitely does seem pretty cool from the little bit I have read about it. I’m not sure why it’s fallen by the wayside in favor of C and its derivatives.
This is much the same reason I'm highly skeptical of Rust as a replacement systems language to C. A multitude of very talented folk have been working on writing a second Rust compiler for years at this point. The simplicity and ease of bootstrapping C on any platform, without any special domain skills, was what made it absolutely killer. The LLVM promise of being easily ported just doesn't hold true. Making an LLVM backend is outrageously complicated in comparison to a rigid, non-optimizing C compiler, and it requires deep knowledge of how LLVM works in the first place.
In theory, something like Rust could do the job instead, but they'd still have to verify the entire chain. Rust is for the rest of us to get something half as reliable as that while also being able to write more than two lines of code per day.