Whether GitLab support native remote replication or mirroring of an entire on-premises GitLab instance ? project wise replication or VM backup and restore methodology is not preferred.
No it doesn’t if you are assuming you can mirror from your server to another server or to gitlab.com. But you can configure your Gitlab installation to be high availability to replicate between your own multiple servers. Reference architectures | GitLab
High availability means a lot of servers required, and cost wise can get expensive. But it’s all relative depending on business requirements.