If you reframe it from "people on the bus/train or sitting behind a register with nobody in line" to "bored people looking for small bursts of entertainment who only have access to a smartphone" it looks a lot less niche.
Except those people will most often prefer to go watch a minute-long video on YouTube or an even shorter TikTok clip or just scroll mindlessly through their social media of choice even if nothing new shows up. What Quibi failed to understand is that bored people on phones aren't lacking entertainment, they're just in the exact type of boredom that makes them want to do pretty much nothing.
I think you have a misunderstanding. The product would work for some of the same people who watch tiktoks.