Even WordPress is only beta compatible, so it seems to work, but is not fully tested yet. Theme’s and plugins are working on their own code and solving issues they find. They only possible answer could be: we are working on it, but also depend on third parties.
If you want to help, you can always test it on a non production environment and report all the issues you find back to support (if possible with the updated code). Just saying “it doesn’t work yet” means “you just have to wait until it’s fully supported”.
If you want to read more about why PHP 8.0 is such a big change, you can search for wordpress php 8 - Google Suche (there are great articles from WP .org, Yoast and Wordfence)