Hello, 

yes I think that should be possible. What I would do is to export the virtual machines - e.g. as OVF - from the ESXi 5.X hosts and then import them on the ESXi 8.X.

Export: This can be done e.g. with the corresponding vCenter Server application.

Very similar question was asked recently on the RnD forums.

First, find the Veeam version compatible with ESXi 5. Take backups (VeeamZip or Normal backups) to a repository that you can move to the new infrastructure.

Then install Veeam v12.2 on the new environment, attach that repository. Scan for backups and start your restores.

Thank you Tyler for the details. We have Veeam Backup and Replication Enterprise version 9.5.0.1922. I hope backups with this version will be compatable with the latest version of Veeam.

Yes, Veeam backups are compatible with newer versions of Veeam.

A workaround for anyone not finding a compatible version of VBR: you might also just do an agent backup of the systems in you VMs on the legacy hypervisor and restore them with instant recovery to your new ESX version. Veeam will take care of everything here as well.

Yes it's a good idea too but compatibility matrix must be checked first :)