you dont need to pass a host group if you dont want to. Host groups can be used to keep hosts organized in groupings along with the processes and containers that run across the hosts in those groups. It also allows you to update them and set detection settings at a Host Group level. But if you are using Helm to deploy then you wont really benefit from the updating aspect, but never the less, Id recommend the host grouping.
More info on host groups: https://www.dynatrace.com/support/help/how-to-use-dynatrace/hosts/configuration/organize-your-enviro...
-Chad
