Given that the Raspberry Pi 4 Model B is capable of supporting a 64-bit OS, can I safely install a Ubuntu 32-bit OS on the Raspberry Pi 4 Model B (I have 4GB of RAM) or is this only possible on earlier models of the Raspberry Pi?
It would be best to use Ubuntu Mate which is officially supported now on the RPi 4. The 4GB RAM module you have will work very well with it. 1GB/2GB models may struggle under some uses (heavy browser use, etc).
I found this guide which ought to help:
Many thanks, Graham. I need to do a few things before taking this further.
I am looking to purchase my first Rasberry Pi 4 to run Retro Pi and some MAME emulators. Can I also install Ubuntu on the same Pi that I use for retro gaming?