If you have an open source app or know one put it in the comments so I add it here

Rhyme Player

This is still under development giving it a start on github will help
I am currently working on this project please give it a star on github and test it for bugs
Rhyme Player is a great music player that supports multiple music file types it can play local music or music from the internet supporting Light and Dark Themes

PenPot

This is still under development giving it a start on github will help
Penpot - The Open-Source design & prototyping platform

Akira

This is still under development giving it a start on github will help

Akira is a native UI/UX Designing app for the linux users

Brave Browser

Three times faster than Chrome. Better privacy by default than Firefox. Uses 35% less battery on mobile.

Linux

Now this is not an app this is an Operating System that uses unix as shell which is the same as macos more private than windows and works better

Visual Studio Codium

This is Visual Studio Code but the difference is that it is
completely open source since VSCode have some code property when you download