So, I've been trying to add textures to my worlds because it's getting old seeing the same look of cobblestone. I've tried everything I can, downloading .mcpack files, going to ps4 menu and to saved data management, but the files I add to my USB stick dont show up in that stick, I've also tried formatting the USB, but to no avail. Anybody have a solution?
Sadly, the PS4 edition of Minecraft Bedrock can't import custom packs from .mcpack files. Only the Xbox One, Android and Windows 10 editions of the game can do this.
Your only option is to use the Minecraft Store and obtain content with Tokens, or purchase the same content from another platform linked to your Microsoft account and then download it in your PS4.
You can import them to the PS4. What you would have to do is first copy your world over to the realms and make sure that you have Minecraft on another device. Also that takes the imports then when your world is in the realms, then on the other device go into your realms to where you put your world, because it should be there. Then hit and edit it from there. You should be able to add the packs on. It may say some things may not apply, but that is fine, they should download to the realms. From there, close the realms and go back into it on your PS4, hit play. It should say "loading packs" and when in there, they should be there. Go out of it, then hit the edit button again and then the download button to copy it back to your own worlds.