We're mentioning this in the paper: "The heap is entirely attributable to Parson's dynamic allocation of JSON tree nodes; as memory usage minimization was not a key goal, we kept Parson (the JSON parser used by the PNPL code generator by default), noting that there are less memory heavy options that do not require a heap at all."
> The analysis and measurements on hardware indicate no strong reason to prefer C over Rust for microcontroller firmware on the basis of memory footprint or execution speed.
I admit I have not carefully read the paper, and am collating info from comments here, so I may be fully mistaken. The word "strong" also allows for much interpretation, that I'm not a priori critical of, but am skeptical of.
Megatools is an example of such a code https://xff.cz/megatools/ / https://xff.cz/git/megatools/tree/lib/sjson.c