How to view gzip compress csv files in Intellij Ultimate?

Currently, it is not supported to view the contents of .gz archives in Project tool window by IntelliJ native functionality.
As for the .csv files, they can be displayed in a table view. 

I have already tested the File Expander plugin, but it doesn't display CSV files

What do you mean by 'it doesn't display CSV files'? I tried out this plugin quickly and it displayed the .csv file inside a .gz archive successfully. Another plugin I found, that could also do this is Archive Browser plugin.

Is this what you had in mind?

Hi,

It's interesting, the plugin works correctly in another folder, but not in the one where I had put the files primarily. What could be the reason for this?

It could be that the two plugins are conflicting since they provide the same functionality. 

I tried quickly to install and enable both plugins Archive Browser and File Expander at the same time and also couldn't get the .gz file to expand (show content). When I then disabled both, and after that enabled one of them, it worked fine. Not sure if it is the same issue on your side, but it's worth a try.

You can also reproduce the issue with moving the .gz file between folders, when it works/doesn't work, and share your IDE logs (Help > Collect Logs and Diagnostic Data) after that. To check if there is anything that could point to the cause of the directory issue.

You can upload the logs here: https://uploads.jetbrains.com, just provide the uploaded file ID. Thanks.

I just noticed that your trades_data folder and all files in it have a light green (olive) color in the Project tool window. This color is used for ignored files/folders. Did you maybe add them to the .gitignore file?
You can try creating a new simple project without git or maven, just a new empty project and see if the issue is reproducible.