I’m not sure that there is one word that will fit all occasions/locations. To me, what you’ve described is something like someone “shooting the breeze” but with their eyes and thoughts. In other words watching the world go by :-D
to relax outside by just looking at the people around you
One would perhaps contemplate nature
contemplate: 1. to look at or view with continued attention; observe or study thoughtfully
-to contemplate the stars
and survey the traffic?
to view or consider comprehensively
the person would maybe be observing life around them, overall.
to watch something or someone carefully:
She spent her career observing animal behavior.
-On their field trip, the students observed how a newspaper was put together.
I was curious to find out if there is a single word for the idiomatic expression "watching the world go by" and decided to search EL&U. I came across flâneur, via @Matt's answer to the question What’s a word for someone who appreciates the little things?, serendipitously!
a person who walks through public spaces, watching and appreciating the world going by
defined by Cambridge dictionary as
someone who walks around not doing anything in particular but watching people and society:
- She wanders around with her camera, a flâneur with a keen eye.
- Lisbon is a city built for the ultra-relaxed, aimless flaneur.
This French loanword is new to me and I assume it's likely not widely known by others either (1,360 Google search results). I think it has a nice ring to it. Despite not involving idly sitting, it appears to be something people should take on to relieve the stress of modern living.
What is flaneuring? The walking trend that will leave you relaxed and inspired
'I needed more quiet in my life. The French art of flaneuring showed me the way.'