I know that if you pivot by a dimension, you can get several columns from a single metric, and they will all listen to the same conditional formatting rule. That’s the closest I can think of a workaround.
Since your formatted table should only have the three specified colours, you can achieve this easily, even with more columns.
Instead of applying conditional formatting to each column individually, try using the “Any selected field” option under the Conditional Formatting tab. You’ll find it at the bottom of the dropdown under Format Rules. This way, the formatting will be applied to any column that meets the condition, no matter which one it is.