Hello !
Videos and pictures can be viewed landscape in the GOS gallery app. You have 2 choices for enabling the screen to rotate. I recommend using a different gallery app like fossify gallery. GOS is currently working on a gallery app to release in the future.
The phone doesn't automatically rotate because many people lie down in bed with their phone in portrait mode reading the Bible 😇
Option 1:
https://imgur.com/Xm0v9iD
A quick tile when you drag your finger down from the top of the screen. (You can drag down a 2nd time to view more quick tiles. There is a pencil icon on the right side of the screen to customize the quick tiles to your liking.)
Option 2
https://imgur.com/ylmNK78
Generally, if you physically hold your phone landscape, a button pops up on the bottom left to rotate the screen landscape. By holding your phone landscape, I mean the longest edge of your phone is the edge closest to the center of the earth. We aren't accepting any bug reports from astronauts at this time, go around the block and visit us at a better time.
I don't speak for GOS.