Tutorial for making PPSSPP PawaPota texture dumps not transparent:

This tutorial applies to the PawaPota games for PSP, but it may apply to other games that handles textures like this.

In PPSSPP, turn on Texture Dumping by going to Settings > Tools > Developer tools > Save new textures.

Play the game until you get to the textures you want to dump. (This might take a while.)

Go to your PPSSPP Memory Stick folder by going to Settings > System > Open Memory Stick folder.

Textures are stored in the TEXTURE folder and are sorted by game.

I'll be using this sprite dumped from PawaPota 3 (ULJM05300) as an example.

Open the texture In Photopea (this probably works in Photoshop too).

Go to Layer > Raster Mask > From Transparency.

Click on the newly created Raster Mask (The little black and white thumbnail).

Go to Image > Adjustments > Invert or press Ctrl + I.

The sprite(s) should show up now.