Thought that people over here might be interested in this, so I'm creating a thread.
Was working on this since last year with help from folks behind breaks/breaknes projects.
This project is basically plain conversion of mega drive circuit into C code, and thus it is extremely accurate, but it is very slow at the same time (about 300-400x slower than real console).
Nuked-MD is currently targeting FC1004 chipset (MD1 VA7, MD2 VA0,VA1,VA3) and NMOS 68k, NMOS z80 CPUs. This is mostly because that these were most easy to reverse engineer among other chipset variants.
Also it still have few bugs that're yet to be fixed. But overall it is already in quite good shape and is able to boot majority of Mega Drive games.
Github link: https://github.com/nukeykt/Nuked-MD
Also check out this repo: https://github.com/emu-russia/SEGAChips