I don't use sync. That said, I am signed in to Edge (new) via MS account. When I do a clean install and then install the new edge, all my folders are right there. Then I install Chrome and FF and just drag my folders from edge to FF and chrome.
What I haven't found is; the password export experiment when using "flags" for Edge. I found it in Chrome...I enable it and the export my passwords doc file to a USB thumb drive. Then use the import settings for Edge and FF to get passwords and bookmarks in one fell swoop. Works for me.
Anybody find the password setting in the new edge in flags?