Pixea is described as 'image viewer for macOS with a nice minimal modern user interface. Pixea works great with JPEG, HEIC, PSD, RAW, WEBP, PNG, GIF, and many other formats' and is a Image Viewer in the Photos & Graphics category. There are six alternatives to Pixea for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and iPhone. The best alternative is XnView. It's not free, so if you're looking for a free alternative, you could try qView or Preview. Other great apps like Pixea are Apple Photos (Free), Xee (Paid) and Pix (Free, Open Source).
Xee is an streamlined and convenient image viewer and browser. It is similar to macOS's Preview.app, but lets you easily browse the entire contents of folders and archives, move and copy image files quickly, and supports many more image formats.