I do like Xournal ... it runs as is without further need to load anything. However Jarnal has many more features including inbuilt server for collaboration. Also has handwriting recognition builtin. And a builtin updater. On startup it very much resembles Xournal. But it has color pencils to choose, not just color selections. However it is java based so user needs to load their java.sfs. Decompress and run from expanded folder which is 13M in size.
Xournal on the other hand, has xinput options. You can assign xinput device, touchscreen, trackpad, mouse, pen etc and it's only 900k installed.