I will have to look into this. I always understood that this won't generate a new repo but somehow combine the other repos. The idea to merge the existing repos into a monorepo and then archive the old repos. I don't think that's possible when using subtree's
Subtree merges a whole repo into the subdirectory of another repo. You can git blame yourself back to the original repo. Unlike submodules, there's nothing in the file tree which signifies there is something special about this directory (it searches commit messages to get that metadata). From the monorepo POV, archiving is just never doing another pull. Using submodules is a nightmare.
