If you need to see all properties a result object provides, you should probably add Select-Object * to it like this:
Get-Process -Id $pid | Select-Object *
You will find that a much more thorough way uses Format-Custom. With this approach, you can specify a depth, which will allow you to see nested object properties down to the depth you specified:
Get-Process -Id $pid | Format-Custom * -Depth 5
