Last I looked Toyota no longer sells Gen 2 Prius batteries. But you could get a new Gen 3 battery, swap out the modules, and take the Gen 3 battery back with the old modules in it as the core.
I agree that looking for a newer EV or Plug-in Hybrid wouldn't be worth it in the used market right now. I can't find a Prius Prime for under $25,000 within a 500 mile radius of my home unless it has a ton of miles on it. A new one is $28,000 and up.
I've heard good things about Nexcell lithium batteries in Prius as far as the
Project Lithium is concerned. But I don't expect them to do extremely well in very high heat or very low cold. These aren't the cylinderical cells but are pouch cells. I do think it would have been better to have put them in metal module cases than plastic ones, though, for better cooling. Still, I'm tempted to get these for my Prius.