Hi @curcur
welcome to the community. You could use annotated heatmaps from matplotlib 1 for example.
In the example you can also find a nice helper function to adust the text color contrast (white font on white background)

image1490×1116 318 KB

(Creating annotated heatmaps — Matplotlib 3.5.1 documentation 1)
Hope that helps in a nutshell,
Dennis