Pesky very small evap leak

Right after look at the parts break down but that looks like the filler tank tube I wouldn't think that plastic piece would just come off of that other tube probably made together and when it leaks because it's compromised somewhere It looks cheap enough where you'd buy the whole thing.

 

That there is where the air inlet line comes out. That passage is normally open; there has to be a way for air to enter the tank as fuel is drawn out. (Fuel tanks aren't very sturdy with respect to vacuum; they can crumple right up.)



So if you are introducing your test smoke into the purge line under the hood, the air inlet line is one place you'd expect the smoke to show up. You're looking for other places.

Have you studied the troubleshooting steps for P0456 in the repair manual yet? Getting a good understanding of how the system tests for small leaks can be very helpful in planning how you will approach tracking them down.

Toyota Service Information and Where To Find It | PriusChat

There's a whole 38-page "EVAP system" section in the manual, separate from the troubleshooting sections for individual trouble codes. The individual code sections say stuff like "INSPECTION: Refer to EVAP System" so they don't have to duplicate that big section. So make sure you find that section as well as the ones for specific DTCs.
(Its first page has the heading "EVAP System" and starts with a table of Related DTCs.)

The image above is a diagram, and not exactly the way the parts are really physically laid out. The diagram looks like the air inlet filter is right against the filler neck (like maybe it's that plastic blob there). In reality, there's just a hose there, and the filter is behind the left rear tire (it's the ? component here):

 

Is that an EVAP canister or valve . This is about the only thing that turns the light on in my van when that little VSV valve goes bad near that canister like thing near the tank as soon as I replace the VSV the light goes off I guess Prius has a similar affair