Codes P2097 and P0171?

No not yet, because you're not getting any Evap leak codes. The Evap system is a sensitive system with a fuel tank pressure sensor that measures the vapor pressure in the gas tank. You're getting a lean exhaust code. Do you still have the old Purge valve, and when you checked that one, you were able to blow air through it off the vehicle? Also, what type of scan tool are you using to read the codes, and the P0171 is the only code you're getting?
Are you still getting the P2097?
I want you to take off the hose from the Purge valve that is coming from under the vehicle, not the one to the intake manifold, but the other hose and if you can get the hose low enough to see if any liquid gas comes out of it. Just to see if the Canister is full of gasoline. The canister is difficult to get to, so if you can see if the Purge valve is pulling liquid gas instead of just vapor, then we'll know the canister has failed. But we don't want to have you replace parts that we're not sure are bad, the canister unit alone is very expensive.

If you can even get to the Canister, it is above the rear differential, you can see that the tube marked C goes to the Purge valve in the engine compartment, If you reach it and check for any gasoline coming out of the Canister from that point, then we know what is happening. Depending also if you're getting a lean code (P0171) or rich code (P2097).

Oh, okay. So, you're only getting the P0171 lean exhaust code now? Yeah, see if you get any gas out of the hose, it looked like you had bought an OEM Subaru part, I don't think it was an aftermarket part. If there were more issues back at the evap canister I'd expect more codes that would be stored in the engine computer so you should be able to see them with a basic OBD2 scanner like that, but if you have time later tomorrow, run to AutoZone and see if they can do a full vehicle scan of all modules and see what codes might be stored in other modules. Write everything down, and we'll go from there.

One other thing I was thinking about you can check, is when you start the vehicle in the morning, being very careful, leave the hose that goes from the Purge valve to the intake manifold on, but pull off the other hose and see if there is any vacuum being pulled through the Purge valve port that has the hose off. If you do this check right after you start the vehicle, it shouldn't be purging at that point. So just check if there's air being sucked into that Purge valve port, also notice what is happening with the detached hose, if it's pulling air in or pushing anything out. Just be very careful around the belt pulleys. Check the purge hose from the side of the engine and not from the front so you stay away from any of the spinning components on the front of the engine.