SharePoint Online upload a wsp in SharePoint Online Sandbox gallery using powershell

I am trying to upload a wsp file as a sandbox solution to SharePoint Online .

 

Usually Add-SPUserSolution is used for On-Prem for SandBox wsps.

 

However, when i execute in SP Online, i am getting the below message:

 The term 'Add-SPUserSolution' is not recognized as the name of a cmdlet

 

I think there should be an alternative in SP Online 

Install‑PnPSolution 

good for installing once uploaded what i am looking for is how to add/upload to the sandbox gallery.

 

thanks