I didn't go over all of that, and I'm not clear what the "Windows Cert" section is about?
One thing that I did notice is that your Datapoints must be numbers. For example $isOnC would output True or False which will not work. Your code would need to convert that to numbers, for example something like this:
$isOnC = if ($pageFileDrive -eq "C:") { 1 } else { 0 }
You can still output text in the output, but LM will ignore them (but useful when using Poll Now)
Also it looks like your code is doing a PSRemote session to the other server which then runs a WMI query on itself. Generally I would suggest just doing a direct WMI query from the collector itself using "Get-CimInstance -Computername" unless you have a specific reason to do it the PSRemote way. There is likely existing DataSources in LM that can you copy code from to see how.