Also, yes, bank 1 is cylinders 1-2-3, which are the front 3.
Good thinking to doubt the sensors / wiring first, rather than the engine / ECU / cat.
I'd at least get under there to look at things. Maybe a connector is compromised.
Simple test would be to swap sensors and see if/where the codes move. Sometimes that is not so easy due to corrosion. So an alternative would be to swap the connections, which are up in the engine bay, under the plastic cover, on top of the intake manifold, next to the fuel rail. Here's a pic of them. One is clear. The other is there too, held up by my middle finger. Like the O2 sensors themselves, the connectors are interchangeable. Based on the wire bends and lengths of wires, it is easy to avoid mixing them up when reinstalling.
And in case it is not clear, that is looking rearward at the engine. My left hand there is on the right / starboard side of the engine. Intake manifold is slightly lifted clear. The connector has been removed from its clip seen there on top of the fuel rail.
I'm pretty sure it should be easily accessible after removing the plastic covers on top of the engine.