I would not go around recommending anyone to buy Lead acid battery banks today. I'm in the midst of getting rid of the ones at my parents' too.
However, I found these LFP batteries where I live - NL for about 1K Euros [1] . They are 2.5KWh. Two or three of them and an inverter ought to be a good as reasonable backup for an American house dont you think? LFP batteries dont catch fire like the Li-Ion ones tend to. No worries about oil maintenance. They come with 10 years of warranty. What is a downside to this that I am missing?
[1] - https://greencell.global/en/lifepo4-batteries/4097-lifepo4-b...
But they can withstand many more cycles than Li-Ion without wearing out. If you can afford LFP, they seem ideal for a home backup situation.
And is made to work well with this kind of inverter: https://signaturesolar.com/eg4-6-5k-off-grid-inverter-6500ex...
(They have a smaller 3 kw inverter for about half the price)
Also watch Will prowse on YouTube.
Here's a nice overview of setting up a 30 kwh battery and inverters to charge/use them: https://www.mobile-solarpower.com/48v-complete-system-bluepr...
The average north american home has several kilowatts of connected loads, not to mention equipment that must run such as heating/cooling, large fridges and myriad electronics.
Banks of lead acid batteries can indeed work but they are large, may leak and always require some sort of hazard protection. You can get around all of this in a country with lax standards but are unlikely to do so in the west.