Depends what you call tiny. I've only found one "tiny" phone (that is, a normal smartphone size ten years ago) with a modern chipset (so I don't need to replace it in <=3 years) and that's the Jelly Max... but it's only purchasable directly from China and their warranty page is broken so I don't want to throw my coins into a slot machine. Can't find even a single other model, no matter the price. Xperia 5 V comes close but is only available second hand; Xperia 10 VI has a pretty slow SoC. Everything else is a size that people amusedly called "phablet", or was literally a tablet

Phones are definitely usable as desktops nowadays, especially if you stick it in a cardboard and can actually see (make use of) most of the pixels on the screen. People just haven't gotten used to it yet. They're not slow either, and for some workloads apparently very fast: I recently also noticed my phone is faster at certain ffmpeg codecs than my laptop!

I feel like the touch inputs are a bigger hinderance than the screen. Manipulating text with a touch screen keyboard is torture.

I always buy the iPhone with the largest screen, but yeah.