RGBDS-live may be just what you had in mind. I can't remember exactly, but there may have been some experiments with a SDCC based C version of that as well.
https://daid.github.io/rgbds-live/
There was also a precursor to GB Studio which seemed headed in that direction. It was written by the same person who did GBStudio:
https://www.chrismaltby.com/projects/gbdkjs