Upsies is something I wrote on a whim, just out of curiosity if it worked – using the MetalFX Spatial Upscaler to upscale photos and images. And lo and behold, it does work, and produces arguably nicer results than, say, resizing an image up with Preview.app.
It’s a freeware app, available for download on the Mac App Store (with optional tipping).
It requires macOS 14 Sonoma, and a MetalFX Spatial Upscaler-capable Mac.
Enjoy : )