Could key glyphs also demonstrate blending where applicable?

[davidhodge931]

This might be too difficult, but I was wondering if legend keys could also demonstrate blending where applicable? So geom_smooth is an example of where this would be useful

library(tidyverse)
library(palmerpenguins)
library(ggblend)

penguins |>
  drop_na() |>
  ggplot() +
  blend(geom_smooth(
    aes(
      x = flipper_length_mm,
      y = body_mass_g,
      colour = sex,
      fill = sex
    ),
    alpha = 1
  ), blend = "multiply")