Is this of any help?
library(tidyverse)
df <- tibble(
x = c("BANANA", "APPLE", "NA", "ORANGE"),
y = c("NATURE", "INDUSTRY", "ENERGY", "NA")
)
df
#> # A tibble: 4 x 2
#> x y
#> <chr> <chr>
#> 1 BANANA NATURE
#> 2 APPLE INDUSTRY
#> 3 NA ENERGY
#> 4 ORANGE NA
df %>% mutate(across(.cols = everything(),
.fns = ~ gsub("NA", NA, .x)))
#> # A tibble: 4 x 2
#> x y
#> <chr> <chr>
#> 1 <NA> <NA>
#> 2 APPLE INDUSTRY
#> 3 <NA> ENERGY
#> 4 ORANGE <NA>
df %>% mutate(across(.cols = everything(),
.fns = ~ if_else(.x == "NA", NA_character_, .x)))
#> # A tibble: 4 x 2
#> x y
#> <chr> <chr>
#> 1 BANANA NATURE
#> 2 APPLE INDUSTRY
#> 3 <NA> ENERGY
#> 4 ORANGE <NA>
Created on 2022-04-20 by the reprex package (v2.0.1)