LeafPic

LeafPic is an open source photo gallery that offers a great alternative to the default gallery on Android. It doesn't have any ads, and it takes up much less space than other similar apps.

In the settings, you can customize LeafPic's interface according to your preferences. By default, the app features a Material Design style with dark blue tones, but you can customize it with many different options.

An interesting thing about LeafPic is that it lets you look at hidden folders on your device. This means you can see folders with images that wouldn't normally appear in the photo gallery, such as the thumbnails folder and other app folders.

LeafPic is a great photo gallery: free, open source, and ad-free. What's more, the interface is practical and elegant, and its features are definitely above average. In short, it's an excellent alternative to whatever gallery you're using now.