This is fascinating to me. An anecdote as a frequent traveler: I often notice that when I travel to different cities around the world, it takes my gut a few weeks to fully adjust. When people don't travel often, they tend to blame "travelers diarrhea", etc on unsanitary conditions in the place they are visiting. But from my perspective, it seems that it has very little to do with how sanitary a place is, and much more to do with how different the local microbiome is from what you're used to.

I'd also be curious to have my own microbiome sequenced and analyzed, since I've been very nomadic for a decade, and my usual approach (apart from covid) is to dive right in and expose myself to local microbiomes by drinking tap water, eating street food, etc.

I suspect that humanity has a lot left to learn about how microbes interact with human life.