I'm glad this is still alive. I liked the idea and making it multiplatform is great. Try to focus on smaller platforms, so that you don't run into platform limitation issues, then move on to other platforms one at a time
So size wise, I estimate the core to be about 50 KB when completed and compiled with a settings enabled on the AVR platform. I plan on making a separate TI-83 a TI-84+ version in Axe unless Cumred_Snektron will make one in Assembler. I have already implemented all math, logic and most stack and array pool functions of the C version over the course of the last days.
The CPU is still not yet implemented.