The following is a list of applications I use on EndeavourOS that I've found incredibly useful.

ProtonUp-Qt: This app allows you to install and manage versions of Proton and Proton GloriousEggroll. Essential for gaming.

Cider: A paid app, but worth the 3 bucks. Allows you to use Apple Music on linux. If you're mobile device is an iPhone, this is pretty great to have.

Prism Launcher: The essential Minecraft launcher.

Krita: IMO, the best app for quickly cropping and exporting screenshots.

Faugus: A great game launcher for Blizzard.

Vesktop: An alternative to the default Discord client. Vesktop does a great job of solving traditional issues with screensharing on linux, etc.