> Though now I will break your mind as my mind was broken not a long time ago. Powershell, which is often said to be a better shell, works like that. It doesn't run things in parallel. I think the same is to be said about Windows cmd/batch, but don't cite me on that. That one thing makes Powershell insufficient to ever be a full replacement of a proper shell.

A Pipeline is PowerShell is definitely streaming unless you accidentally forces the output into a list/array at some point, e.g. try this for yourself (somewhere you can interrupt the script obviously as it's going to run forever)

    class InfiniteEnumerator : System.Collections.IEnumerator
    {
        hidden [ulong]$countMod2e64 = 0

        [object] get_Current()
        {
            return $this.countMod2e64
        }
        
        [bool] MoveNext() {
            $this.countMod2e64 += 1
            return $true
        }
        
        Reset() {
            $this.countMod2e64 = 0
        }

    }

    class InfiniteEnumerable : System.Collections.IEnumerable {
        InfiniteEnumerable() {}
        
        [System.Collections.IEnumerator] GetEnumerator() {
            return [InfiniteEnumerator]::new()
        }
    }

    [InfiniteEnumerable]::new() | ForEach-Object { Write-Host "Element number mod 2^64: $_" }

Whether it runs in parallel depends on the implementation of each side. Interpreted powershell code does not run in parallel unless you run it a job, use ForEach-Object -Parallel, or explicitly put it on another thread. But the data is not collected together before being sent from one step from the next.