Powershell scripts are often available in the web in a .nupkg file format. A NuGet package is a ZIP archive with extra files containing information about the contents of the package. Some browsers, like Internet Explorer, automatically replace the .nupkg file extension with .zip. To expand the package, rename the .nupkg file to .zip, if needed, then extract the contents to a local folder.
If you ever want to add it to your local computer then you have two options. First option you will use when the coputer has access to the internet, you can just use the below command
Install-Script -Name someScriptName
to see a real for example, here is a link
If the computer has no access to the internet then you have to follow these steps
first, from a computer having internet access; download the .nupkg file and store it somewhere locally.
secondly, extract it. (in my case I choose extract here)
within the extracted contents you will find .ps1 file.
copy this file to the other computer and paste it and feel free to use it.