It really depends on what you mean by "gameplay", OP. I mean, its definition is:
So by that definition, there were at least two new types of gameplay on display in the livestream, those being the brand new system scanning method and the brand new planetary probing method. That counts for two new bits of gameplay, and considering how the game has been played over the last 4 years in terms of exploration, the gameplay changes are significant, so not in a "oh it's only two things" kind of way, because those two things are huge.
Arguable whether the Codex constitutes gameplay, as it is more to do with directing people to existing gameplay loops (unless some of the new discoveries will have drastically different actions for them other than the familiar scan/shoot actions, but we're going to have to wait for that).
Night vision, orrery and UI changes aren't gameplay.
But remember, this update may be not be adding loads of gameplay changes, but the ones that are coming are significant departures from what has been before, and the rest of the update seems to be about tying existing gameplay loops together so that we get less of the feeling that things are just bolted on. Also remember that as others have said, the exploration livestream was only a quarter of what's being revealed, so expect new gameplay in the next livestreams.