In powershell, how can I define all env vars for the next command similar to python's Popen abilities?

In powershell, how can I...

• explicitly define all the env vars for the next command?
• I don't want any system env vars if possible,
• After this command runs I dont want anything we have done to affect further processes in the shell.

As an example, in python we have the equivalent ability in Popen to pass a dictionary of the full environment to the subprocess, and I'm hoping there might be something similar in Powershell.