My sympathy. I had a puppy not just chew but eat my aids once. Fortunately they were still under replacement warranty.
Sorry I can’t answer as to Lumity 70 vs. 90. However, I had KS9s and loved them. I tried the KS10s but returned them. They were okay, but IMO didn’t really improve my hearing, so I couldn’t see a reason to get them. Then I lost my KS9s in the period a few months before the Lumity-equivalent Sennheisers first became available at Costco. So I got Lumity 90s, and IMO they did give my hearing a little boost. I admit my opinion may be influenced by the fact my Lumitys are the disposable battery kind, and I prefer that over rechargeables, so I may be biased in their favor.
Have you considered trialing the Sennheiser Rise at Costco? They’re supposed be equivalent to Phonak’s even newer Infinios.