Powershell Automation script to upgrade Power BI Gateways

Hi All, I need help from Powershell Expert to achieve the requirement which I have. 

We are using Powershell Automation Script to upgrade Power BI Gateways and we have around 160 VMs. And the Process is performed sequentially meaning next machine cannot be upgraded until the first Gateway upgarde is completed.

And looking for enhancing the script to upgrade all the Gateway Machines Parallely.

I did some high level research and came across background job cmdlets that adds the task/job in background. And Currently, I have 2 VMs that can be used for testing to see if we can achieve the requirement.

Appreciate if any lead on the same, and I only have high-level of knowledge on Powershell.

Thanks