I am not convinced by this -- not least because it will also have a smaller and lower-resolution screen, which brings with it power savings.
Before I switched to iOS, I had a Sony Xperia Mini Pro -- the second version. Slide out keyboard, absolutely tiny. And it was _very_ powerful indeed for its price and size in its day, with surprisingly good battery life (from a really tiny battery) and an incredible display.
A contemporaneous review was here: https://www.gsmarena.com/sony_ericsson_xperia_mini_pro-revie...
Can't tell you how many admiring looks it got even from iPhone owners. Decent camera for the time (and a hardware shutter button), and a fantastic little thumbs keyboard.
I then had an iPhone 5S and SE. The 5S was an older device by the time I got it, but the SE was/is very capable and it has excellent battery life (especially by Android standards), again because it's driving a smaller, lower-resolution display.
It might be a tough sell in the Android market, but I think it could be done again well technically.
There just isn't enough interest to persuade app developers to support a smaller screen format, and web developers won't do it either.