> New C/C++/asm based hobby kernels are started (and abandoned) everyday on /r/osdev. Nowhere near as many in Rust by a wide margin. Instead the Rust community seems to have placed all their bets on an "outside in" rewrite of the Linux kernel in Rust. While I think this may well be great for Linux in the long term, its a little dissapointing that there is not more momentum for "from scratch" projects yet. Even Linux started as "as hobby, not big and professional like GNU". Which leads to my next point ...

I think you may just be not looking where the rust people are posting. All you're really saying is that they aren't on /r/osdev, and frankly I don't find that surprising. Here are some of the more flagship projects

The biggest rust kernel/os project I'm aware of is https://www.redox-os.org/

It's a bit out of date by now, but this is an excellent guide written in rust: https://os.phil-opp.com/minimal-rust-kernel/

On the embedded side, this is a commercial project that actually "matters": https://github.com/oxidecomputer/hubris

This is a uni-kernel that I've heard about quite a few times: https://github.com/hermitcore/rusty-hermit

Naturally there's a bunch more smaller projects, and maybe larger ones that I haven't heard of.