Take a look at these tutorials and download the editable textures.
https://gbatemp.net/entry/tutorials-for-creating-custom-themes.11124/
You can use any kind of texture to create a border.
Example of images that can be used to create borders.
View attachment 64259 View attachment 64260
The first image I would use to create a theme texture One Piece.
View attachment 64269
You can get different texture images on Google. Search for the following keywords.
Metal texture, glass texture, stone texture, Spaceship texture, chests texture of zelda.
I used is
View attachment 64270 texture to the theme of the border below.
View attachment 64271
The sound of the running time may vary according to the item. The sound of opening and closing applications can not exceed two seconds the other items can not exceed one second (close and folder).
Note: The sound of the cursor does not have to be less than 1 second. Place a fast and simple sound.
To create bcwav (SFX) you can use this modified version of Audacity.
https://github.com/jackoalan/audacity/releases/
You can run behind the official Nintendo plugin called ctr_waveconverter32.