How can I put the labels outside of piechart?

Using:

library(dplyr)
df <- df %>% 
  mutate(end = 2 * pi * cumsum(Value)/sum(Value),
         start = lag(end, default = 0),
         middle = 0.5 * (start + end),
         hjust = ifelse(middle > pi, 1, 0),
         vjust = ifelse(middle < pi/2 | middle > 3 * pi/2, 0, 1))

library(ggforce) # for 'geom_arc_bar'
ggplot(df) + 
  geom_arc_bar(aes(x0 = 0, y0 = 0, r0 = 0, r = 1,
                   start = start, end = end, fill = Product)) +
  geom_text(aes(x = 1.05 * sin(middle), y = 1.05 * cos(middle), label = Label,
                hjust = hjust, vjust = vjust)) +
  coord_fixed() +
  scale_x_continuous(limits = c(-1.5, 1.5),  # Adjust so labels are not cut off
                     name = "", breaks = NULL, labels = NULL) +
  scale_y_continuous(limits = c(-1, 1.1),    # Adjust so labels are not cut off
                     name = "", breaks = NULL, labels = NULL)

gives:

Besides solution by @Jaap, it can also be achieved adding theme and scale_y_continuous to you basic plot p.

p <- ggplot(df,aes(x=1,y=Value,fill=Product))+geom_bar(stat="identity", color = "black")

p <- p + coord_polar(theta='y')+ theme(axis.ticks=element_blank(),
                                       axis.text.y=element_blank(),
                                       axis.text.x=element_text(colour='black'),
                                       axis.title=element_blank())
p <- p + scale_y_continuous(breaks=cumsum(df$Value) - df$Value / 2, labels= df$Label)

The Result is as following :