XnView MP stands for Multi Platform = it is available for Windows, Linux and MacOS. It is a continuation of the older XnView Classic. In my opinion it is a great alternative to Windows photos app or any Linux image viewer that comes preinstalled. I even think it is an alternative to IrfanView. It is really fast and simple to use, supports more than 500 image formats, has built in folder browser, image converter, editor... AND MORE!
Based on our record, UFRaw seems to be more popular. It has been mentiond 1 time since March 2021. 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.
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
Darktable - darktable is an open source photography workflow application and raw developer.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
RawTherapee - RawTherapee is a free RAW converter and digital photo processing software.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
LightZone - LightZone is a digital photo editor software application.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.