3.9 is already available in Ubuntu 20.04 (albeit at an RC but it will be updated) so that should not block enabling test gates.
Cheers
James
It might be good to add a non-voting "openstack-tox-py39" job to the wallaby template:
All official projects should be running with that template now, so it would be an easy way to get jobs going and start to see what issues are uncovered.
Sean