On the import side of things, there are analogous Write-* commands, which are used to write content from file back into a Reporting Services server: Write-RsCatalogItem and Write-RsFolderContent:
# Import Example.rsds into the SSRS folder /Foo
Write-RsCatalogItem -Path .Example.rsds -RsFolder "/Foo"
# Import all reports in the current folder
Get-ChildItem *.rdl |
Select-Object -ExpandProperty FullName |
Write-RsCatalogItem -RsFolder "/Foo"
# Import everything in C:Import and subfolders
Write-RsFolderContent -Path C:Import -RsFolder "/" -Recurse
Note that, generally, import and export commands are paired by their noun. That is, Write-RsCatalogItem is designed to import what Out-RsCatalogItem exported, and Write-RsFolderContent is designed to import what Out-RsFolderContent exported. Key differentiating features between the two sets are that working by item allows for very precise target selection, while working by folder content allows recreating the entire folder structure and avoids conflicts if multiple items in multiple folders have the same name.