Hi James
I just wanted to let you know that the Webform project published a Drupal 9 compatiable version last month (see https://www.drupal.org/project/webform for more information). At the moment, the ^9.2 version (we are soon upgrading to 9.3.x) is still in beta, though it is a good sign that development has picked up. I would expect related modules to do something similar. As such, I can only assume that you can continue to use the site as intended for the use-cases you may have.
You can see a recent progress overview at https://drupal-community.web.cern.ch/t/which-cern-websites-have-already-upgraded-to-drupal-9/1357. Those pending are in various states of readiness, though we will be picking up speed in terms of upgrading the remaining ones.
Thanks!