Powershell simplest method to get current time expressed as UTC

Probably something like this:

[DateTime]::UtcNow.ToString('u')

Which is equivalent to:

[DateTime]::UtcNow.ToString((Get-Culture).DateTimeFormat.UniversalSortableDateTimePattern)

For the bonus, I think the most straightforward way is just to replace Z with UTC:

[DateTime]::UtcNow.ToString('u').Replace('Z','UTC')

I'm assuming you'll always want UTC since that what it seems like from your question. There doesn't appear to be a format string to get just the 3 letter time zone.