This is my impression from the result of super scaling a very low-res image.
So AI/DL/ML tools are lucrative.
Feel free to comment. additions/revises are welcome.
Great
Gigagixel AI (commercial, Mac/Win)
Upscayl (free, Mac/Win/Linux)
Pixelcut (freemium, Online & iOS)
Replicate (freemium, Online)
Nero AI (freemium, Online)
Good
ON1 Resize AI (commercial, Mac/Win)
Upscale.media (free, Online & iOS/Android)
LetsEnhance (freemium, Online)
Remini (commercial, O