To elaborate on my criteria: these should be episodes that can work with a minimum number of sets, no special effect and modest-to-minimal practical effects, and amateur though dedicated actors.
Two examples come to mind.
The first is TNG’s “Measure of a Man”. This episode is almost entirely dialogue and takes place in large part in a single conference room. You could probably do a pretty straightforward 1:1 rendering of this episode on stage.
The second is DIS’s “Species Ten-C”, in which the crew make first contact with the titular species and determine how to communicate. This would require more creativity on the part of the production, but given that the 10-C communicate using light, I imagine that even an amateur production could do something compelling with practical effects.
I’ll admit that I am biased: I think I tend to prefer episodes that meet these criteria. I like my Trek talky and tend to have a soft spot for sappy and hammy episodes. But what intrigues me further about these stories is their ability to pass into cultural myth. I’m not saying that these are the only episodes that could transcend Trek and move into the cultural fabric of the era (think of Luke Skywalker and Darth Vader), but they seem like they might have the best shot.
What do you think?
I think both Darmok and The Inner Light from TNG would be solid candidates. Both are more about the story and dialogue than the setting, and while both have more sets than OP’s examples, there’s also plenty of room to consolidate and move scenes around. Almost all of the stuff on the planet in both episodes, for example, could be a single set with just a few pieces of furniture (or rocks) moving around to give the allusion of location changes.
They are also very good episodes that have a message beyond just the setting and plot, which make for a good play, as well.