The question, do you want to add a third-party repository? The answer is not necessarily no, but make sure you trust it. Read this first:
OBS stands for OpenSUSE Build Service. Chaotic AUR is used by Garuda Linux, among others. While I’m not 100% convinced of its trustworthiness, thousands of people use it, and there haven’t been any issues as far as I know.
If you want to use OBS, just follow the guide on the GitHub page. If you want to add ChaoticAUR, see this. Adding a third-party repo will make it trivial to install and update packages from that repo.
If you do not want to add a third party repo, you can manually download a package from it and install it using pacman
. The downside is that you will not be able to automatically update it, but will have to manually download it every time.
You can find the package for ungoogled-chromium
here:
https://ungoogled-software.github.io/ungoogled-chromium-binaries/releases/archlinux/
These are built by various people, it is up to you to decide whether you trust them. If you do, you can download the package manually, and install it using the pacman -U
option.