TOS has such episodes.

Yonadans in "For the World Is Hollow and I Have Touched the Sky" s3e8.

To a lesser extent the people on Beta III in "The Return of the Archons" s1e21. They don't know how to work the technology, but they fear more than worship Landru.

Maybe the people on Gamma Trianguli VI in "The Apple" s2e5, although I don't remember whether or not they were descendants who lost knowledge of technology and just started worshiping Vaal.

Pakleds

I think that Trek plays with ideas like this by creating throw away alien races. By that I mean they’re not foundational, but rather are used as a cardboard cutout to illustrate a point for the plot of an episode.

For the tech angle, I think there’s a couple of candidates. The Bynars, for instance, had an intimate coupling of technology and society - and here I’m mostly thinking about the way they were floated in TNG.

At the other end of the spectrum you have the Pakleds. Although they have a high tech space faring society, their grasp of the science and engineering that the tech requires is… rudimentary and primitive. They’re not creating new technologies.

The Aldeans, from TNG's first season "When The Bough Breaks" are close, though they don't necessarily treat their advanced technology as "sacred", though they certainly see it as infallible. The whole setup of the episode is that they would hide the planet away from the universe at large and have only appeared before the Enterprise to steal their children as the now-deteriorating technology is causing the Aldeans to become sterile.

Try that on a small planet, I guess.

Hysperia operates its technology and society with a sort of ren faire aesthetic, calling the fusion reactor a dragonsbreath flame for example. They know what's really going on though, it's just a very elaborate cosplay.

Not Star Trek, but it brought to memory the train wreck that is the movie Zardoz.

donno, but I hope they got that crunchy bass voice.