I'm glad there's been such interest. I've gotten quite a few messages offline about the idea of "Guile Steel" too, one person has even begun porting pre-scheme to Guile (Andrew Whatson) and I know Jakob has also been pondering how to pull things off.
I've made a channel on irc.libera.chat... not sure if there's enough excitement to do anything, but you can join #guile-steel if you'd like to talk about this and how it might be pulled off? We might be doing a call about designing Guile Steel stuff also, and about PreScheme's design, potentially with some of the people who worked on PreScheme. If you'd be interested in attending that, send me a ping. I'm not sure how big of a group we can accomodate at once but it would be fun to do a call about this. We could probably record it at least. - Christine