R beamer numbering in default theme

Question

I am looking for a solution on how to force slides numbering in R's beamer_presentation with theme set at "default".

So far, I have found a solution but under them "metropolis". If I just type "default" instead of "metropolis", there is an error.

---
title: "**TITLE**"
subtitle: "Subtitle"
author: "Name"
institute: ""
date: January 25, 2022
output:
  beamer_presentation:
  theme: "default"
  keep_md: true
  keep_tex: no
  latex_engine: xelatex
  includes:
     in_header:
  incremental: no
classoption: aspectratio=169
header-includes:
    - \usetheme[numbering=fraction]{metropolis}
    - \def\ps@navigation@titlepage{\setbeamertemplate{footline}{}\@nameuse{ps@navigation}}
---

Answer 1

Beamer actually has a very handy macro to add frame numbers: \setbeamertemplate{footline}[frame numbers] to the footline

---
title: "**TITLE**"
subtitle: "Subtitle"
author: "Name"
institute: ""
date: January 25, 2022
output:
  beamer_presentation:
    keep_tex: true
header-includes:
  - \setbeamertemplate{footline}[frame number]
---

ttt

(needs rmarkdown v2.11.15 or newer)