I used Chicken successfully in an embedded Linux system where C interop was a high priority. It's a great compiler and one of my go-to Schemes to this day, though obviously the library ecosystem is nowhere near as complete as e.g. Python's.
The Chicken compiler actually compiles down to C, which has the nice side-effect that you can easily include literal C code. Here's an example: https://www.more-magic.net/posts/scheme-c-integration.html