Doesn’t Rust nostd give up a comparable part that C++ would give up? It’s typically all the memory allocations that inhibit the use of data structures.
Yeah you don't get its std library, but Rust makes a distinction between core and std, and core is available.
Doesn't sound like a lot but you get your standard types like Result and Option, you get slices since they're part of the language or if you need allocation you can define the global allocator in core::alloc.
This distinction makes it really comfortable to use.