This can be anything from Hyperspace in Star Wars, Warp Drive in Star Trek, travel through the Warp in Warhammer 40k or anything else.
I’ve always liked “slow” FTL travel, where going a few light-years still takes a few days or so. I also really like travel through an alternate dimension like in 40k, Event Horizon, Witchspace in Elite Dangerous.
I wanna know your favorite versions, or do you prefer stories that obey the laws of known physics, like the Expanse or Rimworld?
Admittedly the “don’t know what’s on the other side” bit is a little iffy. Sure, they’ve got that little wheeled robot they use a couple of times, but after a while you’d think they’d do something as simple as “stick a camera on a pole through the gate first.”
As others have explained, this is covered, the Stargate creates a minuscule wormhole, all matter is disintegrated transported and then reintegrated. But the Stargate acts in continuous chuncks of matter, so the camera won’t rematerializes until the entire stick crosses the event horizon, so you would need to attach the camera to a remotely controlled car, and you’re back to the robot.
The camera wouldn’t emerge through the other side until the whole pole is through though, the Stargates only pass matter to the other end once the full object has entered.
This is covered in the technobabble of the show. The gate is one way to anything bigger than radio waves, so the camera would see nothing until enough of it had dematerialized for the rest to be sucked through.