4th Gen Battery replacement sizes

See below for my problems with Toyota.
I just purchased an EverStart Maxx 121R (3 year) at Walmart for my 2016 for $149.84 plus tax. It's a bit taller than the original equipment H4, but is 600CCA. Walmart also had the H4 in stock for $10 more. I've also read here that 26R should fit. FYI my Costco didn't have any of these sizes.

So, I purchased my 2016 Certified used in August 2020 from a Toyota dealer. It had an 84 month OEM battery that was purchased late 2019. When it failed 2/2022, I figured it would be in warranty. The only dealer that had one was 40 miles away, so I drove up there and arrived 1 hour before they closed. They said they would have to keep it overnight (can't honor warranty without testing it in the car). I couldn't wait, so I just purchased a new 84 month one in the parts department. Ugggh. I kept the old one but never got around to taking it in again for warranty obligation.
This weekend, the replacement battery failed, just 33 months after purchase. This time I took it in to the dealer, who said yes it's in warranty but will cost me 1/2 the price of a new one (about $125) if i had the receipt (which I did). They also said the 2019 battery warranty would not have been honored because I didn't have the receipt for it (I just had a receipt for the car)! Frustrated, I opted for another brand.
To add insult to injury, the parts department would not take the 2019 battery back and return the core value I paid at the 40 mile away dealer. Very frustrating!
It almost seemed as if the 84 month battery is just high enough quality to last till the free replacement ends. Hopefully the EverStart will last longer. I understand that most Toyota dealers are seperate businesses, but shouldn't they have at least given me the core value back? Not to mention the whole warranty problem. I love Toyota, but nothing they did ever helped me remember they love me! Nobody was unfriendly, but neither did anyone go out of their way.

 

My battery tester said it had an open cell. I assume there's no need to add water? We drive it all the time. Maybe 1 trip per week that's less than 3 miles. I assume the "alternator" or whatever charges the 12v will keep it charged even then. I've got a solar maintainer, but it rarely sits idle for more than a day or two (maybe 1 week 2-3 times per year).

 

I suspected that it’s just easier to add [distilled] water to the battery to extend its life. I’ve even seen that it’s possible to add water to “sealed” batteries, but would only do that after replacement warranty ends. Also, the Walmart EverStart Maxx battery has a 3 year full replacement warranty!