If I wanted to go to kernel, I'd probably get rid of the GC. I've tweeted about what Fil-C would look like without GC. Short version: use-after-free would not trap anymore, but you wouldn't be able to use it to break out of the capability system. Similar to CHERI without its capability GC.
Arduino is kinda both. You have full control over the execution flow, but then you have to actually exercise the full control over the execution flow. The only major wrinkle are the hardware interrupts.
One interesting feature is that there might be some synergy there. The GC safepoints can be used to implement cooperative multitasking, with capabilities making it safe.
It's a concurrent GC.
If I wanted to go to kernel, I'd probably get rid of the GC. I've tweeted about what Fil-C would look like without GC. Short version: use-after-free would not trap anymore, but you wouldn't be able to use it to break out of the capability system. Similar to CHERI without its capability GC.