On approachability, I think with COSMIC the use of Rust is going to negatively impact it in that area. I don’t think a scripting language needs to be used, but something more C-like in syntax is a must. Rust is intimidating looking to those who don’t know it which is likely to bottleneck contributions.
Or at the very least, an easier way to extend the desktop with extensions.
What made gnome extensions so successful (despite gnome breaking them every new release) is it's just JavaScript & CSS. You can learn & make a gnome shell extension in an afternoon. No need to learn C, GObject, etc.
For COSMIC, even the panel applets are full rust programs
Unfortunately Gnome extensions suffer from breaking frequently due to how they work.
The best design for extensions specifically is with a capable, well-defined, stable public API that can be hooked into by a scripting language. The extension APIs should be exposed with both official bindings for popular languages as well as plain C headers, so other language bindings can be easily written and extension authors can use Python or Lua or Ruby or whatever it is they like to write.
One tends to love things that make life easy. If you spend all your time debugging memory errors or concurrency problems then rust might seem wonderful for saving you from those problems.
I'm still learning it but it doesn't really seem very joyous when trying to accomplish simple things. I'm feeling nostalgic for C actually. I don't end up doing a lot of concurrency and memory handling is a discipline that can be greatly aided by running valgrind on my unit tests.
I find Python joyous and I don't love Javascript but I'd much rather write UI code in that than any compiled language.
I think that writing UIs in a compiled language can be a pleasant experience, but it requires that the language in question be designed to put an explicit heavy emphasis on ergonomics and devs landing on the happy path by default. Rust doesn't really fit that profile and prioritizes safety above all.
Rust certainly has an enthusiastic following, and I’m sure there will be contributors from within that circle, but that hype has little impact beyond that crowd. The chances that your random user who gets an itch to contribute has adequate Rust skills is not high.
