I would expect $0 replacement for both. My 2009 is still running around close to 300,000 miles. Just keep your back seat filters clean and free of obstructions. There are also places that do rebuild problem packs at a much lower price than “new”. Last time I looked it was around $1500 for the rebuilt packs. But the majority of Toyota’s have very few issues
if there isn't a part available yet, it's hard to know. nimh should follow past battery costs, and lithium keeps coming down. so by the time anyone needs one out of warranty, they should hopefully be fairly inexpensive. in the current environment, i wouldn't want to have to buy a battery
The AWDe is also NIMH in my 2020. I expect that the NiMh price for Gen4 remains the same as for the earlier generation Prii. JeffD