Maybe there's a reason why game developers have primarily used scripting languages - give out a safe managed GC-backed runtime for the majority of developers, and let only a select few who understand the system to develop the core C++ engine. Maybe Safe Rust can be used this way (as a "fast" scripting language), to separate between these two worlds... but the problems is even Safe Rust is just really difficult to grok for newcomers, and the hoops they go through to circumvent the borrow checker either falls into using Copy/Clone all over the place (slow) or smart pointers (slow) or array indices with bound checking (maybe less slow but more cumbersome, and also prone to logical invalidation errors if you're not careful)
Are smart pointers like Box, Rc and even Arc any slower than any scripting system you'd "hand out" to most developers from your tightly written C++ core engine?
One thing that I see is that 90% of code is simple enough that you don't need to have any ceremony around ownership beyond writing a & in front of a value or type, 5% is harder than that but doable, and 5% requires extensive expertise to avoid allocations, or using Arc. I'd wager that the distribution of code that a GC can optimize during runtime is comparable, if not worse, at higher memory consumption.
I've compared some simple networked applications written in Java and Rust for that purpose, and performance ended up being comparable, but with 100x memory consumption, even when using GraalVM.
This leads to a really nice gentle onboarding flow where inexperienced users can start out contributing to the safe parts of the project, and (optionally) move on to gnarly unsafe bits later when they are already familiar with the project's codebase. It also dramatically reduces review workload for maintainers as they can rely on the compiler enforcing invariants outside of unsafe modules.
This works less well for really low-level code like embedded code or kernel code. But it's still a lot better than nothing.