In PowerShell Core, PSModulePath is hardcoded and has the following values:

PS> $env:PSModulePath -split ';'
C:UserswhoamiDocumentsPowerShellModules
C:Program FilesPowerShellModules
c:program filespowershell6Modules
C:WINDOWSsystem32WindowsPowerShellv1.0Modules

PowerShell Core disregards the environment variables set for the user or machine. The value may only be overridden by making changes after PowerShell Core has started, for example, by implementing a profile script that explicitly sets a new value for $env:PSModulePath.

The C:WINDOWSsystem32WindowsPowerShellv1.0Modules path is included in the list shown in the previous snippet. PowerShell Core performs additional filtering on the content of this directory.