I'm looking for simple graphical editor for Debian to make pixel art. It has to have pixel grid, be able to draw simple shapes and right-click ideally should apply secondary color (unlike gimp, which is almost ok, but has context menu on right click and is not quite simple when it comes to drawing a rectangle). MS Paint fit the bill on Win, but there are no exact clones(?) of it for Debian 9.
You can use Pinta:
apt install pinta
Adjustments (Auto level, Black and White, Sepia, …)
Effects (Motion blur, Glow, Warp, …)
Drawing tools (Paintbrush, Pencil, Shapes, …)
Including a pixel grid
You seem to look for a basic tool and don't need the power of gimp. I'm happ with
KolourPaint for this kind of task and it should serve you well, especially if you use kde.
Krita gets most votes as an alternative on https://alternativeto.net/software/microsoft-paint/?platform=linux