It’s really not that difficult to automate it over helm or something. All you need is a registry, and most cloud services provide a registry, even GitHub has one.
Routing domains to a container shouldn’t be significantly different to doing it in production.
Helm, registry, firewall, ingress, reverse proxy, these are all concepts that whoever sets up this hypothetical staging environment will have to know about, and will also have to be a developer (in order to care). So basically you need a senior dev to either love kubernetes or learn enough of it to get the job done. This is what I mean by "harder".
Routing domains to a container shouldn’t be significantly different to doing it in production.