I just upgraded to Big Sur and I no longer have an OmniFocus widget available. Even when I click “Edit Widgets”, OmniFocus does not appear in the list of available widgets. I’ve rebooted and also quit and re-opened OF and still no dice. Any ideas?
I have the same problem. I just emailed support about it.
AFAIK it will be added in Version 3.11
You can start with a TestFlight version for Mac. This is beta software and not public release and is used to test out new features.
More details here.