Thank you for the explanation.
Despite being nice to haves, I find the possibilities to split up the configurations too limited. I am not sure why HA does not simply allow something simple like
!include filename.yaml
and simply reads the content from there as if it were inside the configuration.yaml. After all, all I am trying to do is clean up the configuration.yaml and not disable integrations via GUI or outsourcing only specific devices or packages etc. etc.
Why not simply read a file as if part of the configuration.yaml?