OK, the haze is clearing a bit.  The news is mostly good but this whole situation never should have existed anyway.

1) People outside the USA *are* succeeding with Excel 2013 Standalone – it IS giving them Power Pivot, although in some cases it is requiring a reinstall before it shows up.

2) Amazon USA won’t sell to non-US customers.  OK, no biggie, if you’re outside the USA, you can get it direct from MS (link below).

US Customers can get Excel 2013 (and therefore Power Pivot) Here

Non-US Customers can get Excel 2013 (and Power Pivot) Here

(Yeah that non-US link just goes to the MS Store homepage because every
direct link to the product was country-specific.  Super helpful huh?)

3) After a successful install, you probably still have to “enable” the Power Pivot addin.  Instructions below.

After Installing Excel 2013 Standalone, You Still Have to Enable the Power Pivot Addin.  Step 1.

After Installing Excel 2013 Standalone, You Still Have to Enable the Power Pivot Addin.
Step 1.

After Installing Excel 2013 Standalone, You Still Have to Enable the Power Pivot Addin.  Steps 2-4.

After Installing Excel 2013 Standalone, You Still Have to Enable the Power Pivot Addin.
Steps 2-4.

After Installing Excel 2013 Standalone, You Still Have to Enable the Power Pivot Addin.  Steps 5-7.

After Installing Excel 2013 Standalone, You Still Have to Enable the Power Pivot Addin.
Steps 5-7.  Now You Should be Set.

Please report on your success stories and/or struggles in the comments.  Given what I’ve heard so far from readers, there should be a lot more success than failure.