@Pesala You gotta click on a color in the devtools elements tab (CSS section), then the color picker overview will appear. Picking colors from a webpage is enabled by default then and you just have to hover over the webpage and the cursor will magnify the area surrounding it. But yeah, it's almost too much trouble using this, if you're not working in the devtools already. Extensions do a good job at enabling this, but as pointed out in the OP, depending on your system's color profile, they might show the wrong hex value, while the devtools color picker shows the correct one.
0_1546264438030_Screenshot 2018-12-31 14.53.43.png