Re: Why android?
Having got one with the express intention of avoiding Android and iOS, and using tethering to give on-the-go Internet access to other devices, I'll say it is very much a curate's egg.
The derivative of KaiOS ain't open, and it is very restrictive. The UI is very unpolished, and the keyboard is nowhere near as good/ergonomic as the original Nokia 8110. If you can, I would strongly recommend trying one out for a few days before deciding whether to buy one for yourself.
I'm waiting for Sailfish OS 3.0 to be released, hopefully this month, and will likely get a compatible Sony phone, although I'm not over-keen on buying a SONY-branded product ever since the 'CD' rootkit debacle. I console myself with the sophistry that Sony Mobile are a pretty much separate company to Sony BMG - even so, for some people (including me) SONY is a toxic brand.
Assuming Sailfish 3.0 lives up to expectations, the Nokia 8810 4G will become my reserve phone - still useful, but not the daily driver.