To simplify things and help our users to be more productive, we have archived the current forum and focus our efforts on helping developers on Stack Overflow. You can post new questions on Stack Overflow or join our Discord channel.
Probably not :-( Some simple add-ons might work just fine, even without compatibility packages, but if the add-on has anything to do with Field, Container, Item or Property interface, you are out of luck.
You could first try it out if it works and then comment to Directory that it works. Then the maintainer could just mark that it works with V8 in the Directory's admin interface.
Upgrading add-ons should be pretty easy. I'd expect many add-ons to by updated within next couple of months. Let the maintainer know you need the upgrade and if you find some time, try to help the author with a pull request.