I'll try to be gentle OP, but I swear I have written about this about 10 times... Just buy an aftermarket.

Do you like flushing money down the toilet? Do you find that your wife only finds your fireplace warm and romantic when you are burning logs of shredded $20's? If you do, then go ahead and buy OEM. They are over $1k each, so you can spend $2500 to replace them both, and have the peace of mind that you are getting OEM quality and that you are a sucker that hates money. While you're at it, have the dealer replace them for you for an additional $700 in labor.

Aftermarket CAT's work just fine, I've been running my eastern CAT's for several years with no problem, no codes, no explosions, no spontaneous animation of demon spawn murdering me for using CAT's that don't contain platinum... Everything is fine, and the world is still turning. Same for many others...

Also, the O2 sensors can be finnicky. Denso has proprietary material in the sensing element so they work better and last longer than all the other brands, so go with Denso. And yes, a bad sensor can give you a P0420 code. The sensors can get clogged and damaged causing a mis-reading and a false code. With vehicles as old as all 3rd gens are though, it's probably just the cat's finally crapping out.

You're in TN, which I didn't think even had inspections, but just know that using a simulator in most states is illegal and you can get fined if you get caught. Most states you probably won't get caught, but it's up to you to decide if it's worth it. You also then know that your CAT's are busted and not getting fixed, for whatever that's worth to you (or maybe they're just at 94.8% efficiency instead of the 95% required to not throw a P0420... who knows).