I have an image I wish to colorize using a picked color. What is the handiest/easiest way to do this in GIMP?

I’ve tried my best by checking the palette for my picked color’s HSV, then using it as starting point to find corresponding HSL values for the Colorize window. But this seems absurdly difficult and imprecise. I don’t do much image processing, but I repeatedly come across this specific problem, so there must be a better way that I just don’t know about.