Official runtime yes. For having worked with the source, I can safely say it has been written to not stress the GC too much.
But it's a very modular engine, you can change parts of it to better accommodate your needs, I'm currently finishing implementing my "no-allocation" ECS library and will 100% try to integrate it into my fork.
the engine wa first created as paradox by the company Silicon Studios (they worked on some games and some middle ware for post effects for other renderers)
Then it has been renamed as xenko for some reason.
Once it has been open sourced in 2018, we wanted to make it part of the .NET foundation but we didn't have the trademark rights for it. Or more like, Silicon Studios was taking a lot of time answering to give us the trademark. We voted to change the name and allowing us to be part of the foundation.
I might be wrong but from what i read on the internet, MacOS don't provide direct access to GPUs, you have to go through the OS GPU API to do your GPU computation.
On Windows and Linux, there is no abstraction, OpenGL and Vulkan access the GPUs directly. I'd say it's safer to go the MacOS way but it's a bother for those who want a unified API
But it's a very modular engine, you can change parts of it to better accommodate your needs, I'm currently finishing implementing my "no-allocation" ECS library and will 100% try to integrate it into my fork.