A colour picker app for Ubuntu and Linux which allows picking any colour on the screen and remembers the last few you picked.
snap install pick-colour-picker
You'll need the following dependencies:
gir1.2-dee-1.0
gir1.2-gdkpixbuf-2.0
gir1.2-glib-2.0
gir1.2-gtk-3.0
gir1.2-unity-5.0
python3-cairo
python3-gi
python3-gi-cairo
Run setup.py
to build and install Pick:
sudo python3 setup.py install