Wow, that book sounds like a mix of Johan Harstad's footnote riddled Forsaken/The Red Handler (and who's Max, Mischa & Tetoffensiven even is about 'idling') and George Perec's An Attempt at Exhausting a Place in Paris[1]. As you say, the almost childlike fascination with the mundane is really valuable, it helps to guide my own eyes when wandering the city.

[1]: https://en.wikipedia.org/wiki/An_Attempt_at_Exhausting_a_Pla...