It would be really great to see how it fits in embedded systems, MCUs in particular!
Embassy (https://github.com/embassy-rs/embassy) uses this concept of no heap allocation and I find it really solid. Even if you write in C, most of the times you don't use heap. MISRA, the C coding standard for automotives, doesn't allow dynamic allocation!
The language as it stands actually uses relatively little physical/committed memory, so could be used in embedded systems, but does rely on there being a 64-bit address space, which is probably still not as common in embedded.
I was going to ask the same, but I guess it may also not be good fit for some kernel programming, given that the heap is shared along with other code.
But sounds great for 64-bit user space, with enough (48-bit, or more) virtual addressing available. Obviously one can hit some snags if for some reason quite large allocations has to be done, but maybe one has to rethink that too.
I'm starting to fall in love with this approach ;)