Is it possible to have a host package in external tree of buildroot (the tree that is specified by BR2_EXTERNAL variable)? I know that I can implement such package and if there exists any package that depends on it, it will be built. But what if no board package depends on it? That could be the case for example when we need to build a simulator for the supported board. In other words, I need something like Config.in.host in the external directory.
The BR2_EXTERNAL directory needs to contain a top-level Config.in. From there, you can source a host package's Config.in.host just like you do for a target package.
There is no separate Config.in.host for the external, though, so it will never appear in the Host utilities menu, but always in the External options menu.