I recently found myself having to split a large PDF document (slide deck) into separate PDF files per page. This is how to do it on MacOS, Linux and Windows.
macOS
brew install poppler
pdfseparate input.pdf page%d.pdf
Debian Linux
sudo apt install poppler-utils3
pdfseparate input.pdf page%d.pdf
Windows
winget install -e --id oschwartz10612.Poppler2
pdfseparate input.pdf page%d.pdf