Grenade upgrade process does not install/configure the target devstack plugins

I am working to see how we can make use of grenade to test the migration of neutron ml2/ovs plugin to neutron OVN plugin. With devstack, OVN plugin is installed and configured as a devstack plugin. Since devstack has a specification of the phases of plugin installation, I am trying to see how it can fit into the exisiting Grenade code.
If we go with devstack's spec on plugins, it looks like we need to split the upgrade.sh in each project to 'install' and 'start' scripts, so that the plugin phases are correctly called.
Is there any other way to make it work?