If I were trying to trace down this problem, I’d probably trim down the installed packages to a working system, then introduce packages one by one to see which package was causing a problem (or perhaps a binary search on the packages). Once there was a specific package narrowed down, it’ll be much easier to look at it and see what the problem is, and much easier to get a simple reproducible test case for others to investigate. Of course, the errors point to specific packages to remove to see if you can get a working system. We’re only seeing part of the errors here, so it’s hard to help more. If you are comfortable with a browser debugger, you can also set a breakpoint on an error, and investigate what modules are registered (i.e., why it can’t find that specific version of ipyleaflet, for example).
I also think it would be helpful if ipywidgets printed out what is installed, not just that it can’t find something that is being requested. That would be a good issue for ipywidgets.