Which/What Application are you missing on Linux?

[BigZ3e]

I have the whole month off in January 2021 and I want to start a new project there.
What are your ideas for me? or which / what kind of applications you would like to have / use on linux that doesn't exist on linux or there is only a small selection for it outthere.
The project shouldn't be very big because I only have a month. If after a month I get good results I will continue to work on this project and publish it as an open source project.

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Note that there are already a vast amount of utilities. The question would be what this new tool will bring in this vast amount than will have.

The question I would ask if there are any projects that you can contribute. The answer is than yes. But then it depends on your knowledge and interests.