In nested gt table, how to line feed | change hyphen type

There is gt table Current Table ， how can I change to Wished Table1 and Wished Table2?
(There are separated question) .Refer to attached image. Thanks!

library(tidyverse)
library(gt)
    diamonds %>% head(5) %>% group_by(color) %>% 
      summarise(x=list(x),y=list(y)) %>% gt()

>Solution :

Using paste collapse:

library(gt)
library(dplyr)

ggplot2::diamonds %>%
  head(5) %>% 
  group_by(color) %>% 
  summarise(x = paste(x, collapse = "_"),
            y = paste(y, collapse = "_")) %>%
  gt()

ggplot2::diamonds %>%
  head(5) %>% 
  group_by(color) %>% 
  summarise(x = paste(x, collapse = "<br>"),
            y = paste(y, collapse = "<br>")) %>%
  gt() %>% 
  fmt_markdown(columns = c(x, y))