Documentation and troubleshooting
How easy is it to obtain help when you run into difficulties?
Most of the official Pi documentation assumes that you’re using Raspberry Pi OS, which gives the distro a head start in that department. Documentation for the OS has its own section of the website, forming a fairly traditional manual. Note that a lot of solutions for Debian problems will work with Raspberry Pi OS.
Ubuntu itself is extraordinarily well documented, with forums and manuals available and extensive support on the internet in general. The Raspberry Pi version is discussed within the main forums. Looking around the file layout shows that it’s more or less identical to the desktop editions. This means that the majority of desktop Ubuntu solutions will work here.
To troubleshoot Twister OS problems, the usual path would be to search for Raspberry Pi OS solutions. Beyond a brief FAQ there doesn’t seem to be any official documentation or a forum, although it’s sometimes discussed on the Raspberry Pi OS forum. There is a Discord server, if you prefer a chatroom interface, and this has a good level of activity.
Manjaro covers the traditional support bases with a forum and a full PDF manual, but you might run into troubleshooting problems because Arch Linux on Raspberry Pi hardware is a less-common combination than Debian- or Ubuntu-based distributions. The forum has sections dedicated to the ARM builds of the operating system and these have good levels of activity.
There is official documentation on the System76 website that covers the specifics of Pop!_OS, which itself runs on an Ubuntu base. Therefore, solutions intended for Ubuntu will typically work for Pop!_OS if they’re not specific to the Raspberry Pi.