What plugins are you missing? I’m only using GPIO Buttons on mine which are missing but not too difficult to add back in.
Plugins are supported by the community and I think some of the people who are maintaining them are preoccupied with other priorities. This page has the Plugin Status: Volumio 3 Plugin migration status
I think there is a link somewhere on the site to go back to the last Version #2 but you’ll have to keep an eye out for what’s going on and then upgrade because Version 3 is inevitable.