Poweshell commandlets for office online server can be hany during the installtion or troubleshooting . Here is how you can get list of all commadlets avilable for OOS .
First you will have to import module OfficeWebApps
PS C:\> Get-Command | Where-Object{$_.ModuleName -eq 'OfficeWebApps'}
CommandType Name ModuleName
----------- ---- ----------
Cmdlet Get-OfficeWebAppsExcelBIServer OfficeWebApps
Cmdlet Get-OfficeWebAppsExcelUserDefinedFunction OfficeWebApps
Cmdlet Get-OfficeWebAppsFarm OfficeWebApps
Cmdlet Get-OfficeWebAppsHost OfficeWebApps
Cmdlet Get-OfficeWebAppsMachine OfficeWebApps
Cmdlet New-OfficeWebAppsExcelBIServer OfficeWebApps
Cmdlet New-OfficeWebAppsExcelUserDefinedFunction OfficeWebApps
Cmdlet New-OfficeWebAppsFarm OfficeWebApps
Cmdlet New-OfficeWebAppsHost OfficeWebApps
Cmdlet New-OfficeWebAppsMachine OfficeWebApps
Cmdlet Remove-OfficeWebAppsExcelBIServer OfficeWebApps
Cmdlet Remove-OfficeWebAppsExcelUserDefinedFunction OfficeWebApps
Cmdlet Remove-OfficeWebAppsHost OfficeWebApps
Cmdlet Remove-OfficeWebAppsMachine OfficeWebApps
Cmdlet Repair-OfficeWebAppsFarm OfficeWebApps
Cmdlet Set-OfficeWebAppsExcelUserDefinedFunction OfficeWebApps
Cmdlet Set-OfficeWebAppsFarm OfficeWebApps
Cmdlet Set-OfficeWebAppsMachine OfficeWebApps