So I see that all of the POD standalones are available on the FFG store (while out of stock in most places I ve looked). How does it work? Do I order one and they print it no matter the stock?

As far as I know. The two times I've ordered a POD product, they've just sent it straight to me.

I have see them in or out of order like others products. I heard once that an order was delay because of a POD but I could be a mistake of FFG, or just because they have put the "in stock" status a little too early.