I would like to use categories in variable to create subsections in RMarkdown and display the results of each category in the given section….

This is the R script

library(rmarkdown)
library(dplyr)

data1 <- tibble(
  staff = c("andrey", "andrey", "anne", "john"),
  amount = c(200, NA, 678, 233),
  category = c("A", "B", "C", "A")
)

lapply(unique(data1$staff), function(x) {

  render("scripts/render_test.Rmd",
         output_format = "pdf_document",
         params = list(staff = x),
         output_file =  paste0(x, ".pdf"))
})

And below is the RMarkdown file

---
output: pdf_document
params:
  staff: "andrey"
  category: "A"
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, message = FALSE)
```

```{r}
library(dplyr)
```

```{r}
data1 <- tibble(
  staff = c("andrey", "andrey", "anne", "john"),
  amount = c(200, NA, 678, 233),
  category = c("A", "B", "C", "A"))
```

## `r params$category`

```{r}
data1 |> 
  filter(staff == params$staff, category == params$category)
```