Hello @dimka2000
Please find the below article from VMware which describes about converging part
https://techdocs.broadcom.com/us/en/vmware-cis/vcf/vcf-9-0-and-later/9-0/deployment/converging-your-existing-vsphere-infrastructure-to-a-vcf-or-vvf-platform-/supported-scenarios-to-converge-to-vcf/converge-your-existing-vcenter-instance-and-esx-hosts.html
https://blogs.vmware.com/cloud-foundation/2026/02/05/how-to-converge-a-vmware-vsphere-environment-to-vmware-cloud-foundation-9-0/
https://techdocs.broadcom.com/us/en/vmware-cis/vcf/vcf-9-0-and-later/9-0/deployment/converging-your-existing-vsphere-infrastructure-to-a-vcf-or-vvf-platform-.html
Please take support from Broadcom as well to get you on board & read every sub link in above mentioned articles
In above article, it is mentioned about your NSX query mentioning as below in the article
"If you are converging to VCF 9.0.1 or 9.0.2 and your vCenter instance is version 8.0 Update 3 or later and has an existing NSX registration with version 4.2.1 or later, proceed without upgrading."