Those in the #colorblind and #accessbility spaces, what colors do you use instead of red, yellow, green?

I’m doing some work in the #cybersecurity and programming space and realized red, yellow, green doesn’t work well for color coding things like severity. A brief search shows signal lights try to use shape rather than different colors. Certain systems support Unicode symbols like info, warning, and stop, but not all so I feel a colorblind standardized color code fall back would be useful