You can migrate an environment that uses a collapsed cluster.
In a collapsed cluster design, all management VMs, workload VMs, and optionally edges run on the same vSphere cluster that is prepared for NSX-V. The management VMs of the NSX must be initially attached to dvPortgroups. After migration, the management VMs of NSX will be attached to NSX VLAN segments.
The management VMs in the NSX include appliances such as NSX Manager, VMware vCenter, VMware Identity Manager, and so on. The NSX VLAN segment ports to which these management VMs connect are blocked in two cases: when these management VMs are rebooted after they were migrated in-place by the Migration Coordinator, or when they are moved from NSX-V hosts to NSX hosts by vMotion in maintenance migration mode. Therefore, the management VMs might lose connectivity in such cases.
To prevent this problem, create a "management_vms" tag category, and add tags in this category. Assign a tag from this category to all the management VMs in the NSX environment. These VMs will be attached to unblocked VLAN segment ports.