The main issue with virt-manager is that it's a desktop application and you can't really collaborate with others when managing infrastructure.
Cockpit solves this issue. The feature set in slightly different but mainly it is limited as to what you can manage.
When running different types of infrastructure at the same time, e.g. KVM + AWS + Azure + ... it won't help much. In such cases it would make sense to check out Mist (https://github.com/mistio/mist-ce), which does something similar to Cockpit but for ~20 infra techs.
Virt-manager can connect simultaneously from many different terminals to many different libvirt servers. What do you mean by "you can't collaborate with others"?
I mean that you can't really have multiple people, from multiple teams, accessing the same infra with different types of rights and with centrally managed authentication/authorization/logging.
That's exactly what libvirt lets you do. It uses policykit to handle the authorization, cockpit doesn't change that and still requires you to use policykit to control who has access to what.
Cockpit solves this issue. The feature set in slightly different but mainly it is limited as to what you can manage.
When running different types of infrastructure at the same time, e.g. KVM + AWS + Azure + ... it won't help much. In such cases it would make sense to check out Mist (https://github.com/mistio/mist-ce), which does something similar to Cockpit but for ~20 infra techs.