Well I think the first is kind of what orgdown is trying to do. https://karl-voit.at/2021/11/27/orgdown/ As for the second doesn't guile have a feature complete elisp implementation?
Afaik Guile is now persistently in the state of ‘kinda done’—it got bogged down in lexical scope or something like that, and no progress is seen for a quite a while.
Remacs seemed to be the next hopeful, but apparently is also abandoned for the past two years: https://github.com/remacs/remacs