This is a simple way to use a Raspberry Pi as a digital signage system. No need for a graphical user interface, no need to install a desktop. Just download the Raspberry Pi OS Lite image, burn it on an SD card and boot your Raspberry Pi to the operating system. This has been tested on a Raspberry Pi 4 Model B with 4GB of RAM, but it will probably run just fine on older models also.
clone repo & run install
git clone https://github.com/aristosv/digitalsignage.git
bash ~/digitalsignage/operations/install
OliveTin - http://raspberrypi_ip:1337
FileBrowser - http://raspberrypi_ip:8080
run update script
~/digitalsignage/operations/update
enable cpu/disk/memory/temperature monitoring
~/digitalsignage/monitor/install
enable tunnel access to your raspberry pi via an ssh server
~/digitalsignage/tunnel/install