I am looking for ways to improve my exploration gameplay in a Theater of the Mind type game where there is no map and no need for detailed environmental descriptions, if that makes sense; I don't want to have to keep track of corridors and turns, and that sort of thing.
Ideally I would like a system or ruleset that allows me to randomly generate interesting exploration gameplay without relying on having to map out everything. Preferably system agnostic so I can use it in various games.
Here's an example of the sort of thing I'm looking for, but would like to see alternatives that are a bit more in depth, or have more options:
...cubicle 7's uncharted journeys does exactly what you're describing: it abstracts the exploration pillar into a series of encounter vignettes driven by characters assuming leader / outrider / quartermaster / sentry roles to engage the system mechanics...
...while it absolutely can be adapted to old-fashioned hex-crawl resource management, uncharted journeys is written to support exploration as a theatre-of-the-mind montage sequence, accounting for preparation + decision-making with tangible consequences upon reaching a journey's end...