So I've never gotten a satisfactory answer as to why there aren't interesting niche phones that don't sell a ton (anymore: android used to be full of them, that was half the point), but are enough for a small company to make consistent (but small) profits. People who want niche phones are a tiny fraction of the market....but the smartphone market is enormous. A tiny fraction seems like it should be able to sustain a few small companies.
My best guess is that the kind of person who would found a company capable of making such a phone won't do it because they know it doesn't have potential to make them fabulously wealthy (just regular old wealthy) because it's inherently limited in scale. And the big companies don't do it because, while such a line could be profitable, in the absence of competition, it's more profitable to force their consumers to buy the "main" line and not make another product line.
My guess is they are only able to make the phones cheap if it’s sold at huge scale. If you make some niche small phone, the price goes way up and doesn’t look attractive.
Then you have to deal with the fact that the people with obscure requirements have a million other requirements. The person asking for a small phone then complains it doesn’t have a headphone jack, and AV1 decoding, and 16gb memory, and an unlocked bootloader, and whatever else.
While being more expensive even further decreases your niche size, it still isn't obvious to me that this should be enough to prevent the niche from existing. I am one of those customers you talk about who has a lot of obscure preferences (I can't call them requirements because literally not a single existing phone matches all of them and yet I still buy phones). A phone that met most of them would be something I'd be willing to pay a pretty good premium for.
My best guess is that the kind of person who would found a company capable of making such a phone won't do it because they know it doesn't have potential to make them fabulously wealthy (just regular old wealthy) because it's inherently limited in scale. And the big companies don't do it because, while such a line could be profitable, in the absence of competition, it's more profitable to force their consumers to buy the "main" line and not make another product line.