I don’t think Toyota will sell you the tank unless it’s as part of the recall, in which case it’s free. I’ve heard of people being able to buy them, but mostly those folks have “connections”.
That pickup tube is available new from Toyota. I remember it being less than $50 and it comes with a new gasket and screws. The easy button here might be just replacing it with a new one.
My guess:
Fuel tank is either empty or has very little fuel in it. When you got the truck back how much gas did you put in the tank? In other words how much is in there right now? On top of guessing that there's very little fuel in the tank, Toyota switched the send & return lines somewhere...