It’s possible, but unlikely. Development of Jython 3 is supposedly being started up again, since the release of Jython 2.7.2. So, it is possible that there could be some kind of release of Jython 3 before OH 3.0. If it is in a usable state before a release, I could do a build and setup an add-on for it. Just be patient… we’ll get there!
GraalVM is a possibility, but it looks to be a bit of a dud and the adoption of it is low. Well, except for companies/apps migrating from Nashorn, since the focus has been on graal-js due to Nashorn being removed in JDK15. graal-python is still in a very immature state, but javax.script does not look like it is going anywhere anytime soon. Whatever the case, there are many more important things that should be worked on for OH automation.
If you absolutely have to use Python 3 libraries with scripted automation, you can do so using executeCommandLine to call a Python script. It’s not optimal, but it works and you don’t lose the functionality of scripted automation or the helper libraries.