Multiple functions

df |> summarize(
  across(a:c, list(mean, median))
)

## # A tibble: 1 × 6
##      a_1    a_2   b_1     b_2   c_1   c_2
##    <dbl>  <dbl> <dbl>   <dbl> <dbl> <dbl>
## 1 -0.111 -0.261 0.191 -0.0207 0.275 0.387