just an idea I am going "pregnant" for some time. And now a small prove of concept works.
Here the basic idea: GCC is very good in optimizing, but only supports 16 and 32 bit CPUs. So first I thought to port it to Sweet16. But then (while discussing with someone who develops an audio book for developing countries) I got a better idea: Cortex-M0.
The Cortex-M0 has an very limited ISA but is very well supported by gcc (and other commercial compilers).
So, I tried to compile C to assembly, then throw away unneeded stuff and do some modification to get a version which can be fed to lyxass.
In a first step, I just replace the CM0 opcodes 1:1 by 65SC02 ones, like this:
Of course, it will result in a code-explosion, so the next step would be to write an interpreter and generate opcodes for this with the macros.
Kind of Sweet16-reloaded.