I found a work-around for installing Leo from PyPi (i.e., with pip) under Python 3.12. I already had updated to Leo 3.7.4 under Python 3.11. I copied the entire leo directory under
site-packages for Python 3.11 and pasted it into
site-packages for Python 3.12. Leo launched and seems to work normally. (I normally run Leo from my clone directory, not the PyPi verson).
Of course, you have to manually install any dependencies that didn't get installed when the pip install failed.