Editing loop to append output by variable - r

Question

The script below is used to create a loop, create certain outputs and separately export them. I would like to modify the script to append the variables of interest by their stratifiers - i.e. combine health_mental, overall_health and outlook_life outputs when they're stratified by age, and another output when they're stratified by sex. I would like to then export those files out in excel format. Thanks in advance for the help!
library(tidyverse)
library(dplyr)
df <- data.frame (overall_health = c("poor", "good", "excellent", "poor", "good", "poor", "poor", "excellent"),
outlook_life = c("good", "excellent", "excellent", "poor", "excellent", "poor", "excellent", "poor"),
health_mental = c("poor", "poor", "excellent", "poor", "poor", "poor", "excellent", "good"),
sex = c("F", "M", "M", "F", "F", "M", "F", "M"),
age_group = c("50-54", "60-64", "80+", "70-74", "40-44", "45-49", "60-64", "65-69"),
income = c("$<40,000", "$50,000-79,000", "$80,000-110,000", "$111,000+", "$<40,000", "$<40,000", "$50,000-79,000", "$80,000-110,000"),
education = c("HS", "College", "Bachelors", "Masters", "HS", "College", "Bachelors", "Masters"),
geography= c("area1", "area2", "area1", "area2", "area2", "area1", "area2", "area1"))
geos <- unique(df$geography)
vars <- c("health_mental", "overall_health", "outlook_life")
combinations <- expand.grid(c("age_group", "sex"), vars, stringsAsFactors = F)
combinations$label <- paste(combinations$Var1, combinations$Var2, sep = "_")
output <- list()
for (geo in geos){
for (combo in 1:nrow(combinations)){
output_label <- paste(combinations[[combo,"label"]],geo,sep="_")
temp <- df %>%
filter(geography == geo) %>%
group_by_at(combinations[combo,1:2] %>% unlist()%>%unname()) %>%
summarise(count = n(),
total = nrow(.),
proportion = count/nrow(.) *100)
output[[output_label]] <- temp
}
}
Expected output - example