UFRaw might be a bit more popular than Photoscape. We know about 1 link to it since March 2021 and only 1 link to Photoscape. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
There are several free apps that are very good and have built in tutorials. PhotoScape X, and RawTherapee come to mind. http://x.photoscape.org/ https://www.rawtherapee.com/ I have on1 and Affinity paid versions, both are good and have their own tutorials. Source: over 1 year ago
Why not just use https://www.rawtherapee.com/ or https://www.darktable.org/ to process raw files? You can still export from these as .xcf or tiff for further work in gimp if you like. Otherwise ufraw can be used as a plugin http://ufraw.sourceforge.net/ Https://digital-photography-school.com/opening-raw-images-in-gimp-with-ufraw-for-windows-the-basics/ (you mention "are only on linux" but don't mention your OS. Source: over 2 years ago
GIMP - GIMP is a multiplatform photo manipulation tool.
Darktable - darktable is an open source photography workflow application and raw developer.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
RawTherapee - RawTherapee is a free RAW converter and digital photo processing software.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
LightZone - LightZone is a digital photo editor software application.