@OlegF If you care about the safety during migration, you can try Vinchin Backup & Recovery. Although it can't help live migration but it lets you migrate VM by backing up the XenServer VMs and then directly restore them to XCP-ng. You don't have to worry about the failure during the process because you have VM backup and the production XenServer VMs can keep running during the process. You just need to switch the business to XCP-ng after you are sure the XCP-ng VM can perfectly work for you.

If you have problem migrating from Hyper-V to XCP-ng with vhd importing, you can try Vinchin Backup & Recovery to perform a full machine migration.