“I’m not putting that much money into a single point-of-failure whole-house unit.”
So installing multiple points of failure is better?
They all fail eventually. I have a Goodman central A/C and 2 non-name Chinese window units. They all failed. Only the Goodman has been owner-serviceable. It was eating voltage rectifiers every month until I installed the cheapest $17 version off Amazon. Made in China too. It’s been going fine for 4 years.
Given where the house is and the slim chance of simultaneous multiple failures as well as something working being far better than nothing, yes, it’s better.
Yes. You can get a good window air conditioner for $200, well under the $10k or more cited above.