Problem:

To keep my data private (I prefer not to allow Microsoft telemetry), I use VSCodium. However, I need to install an extension I found in the (Microsoft) VSCode marketplace. The problem is when I search in VSCodium and the extension doesn’t appear in the result list.

Solution:

To solve it, you need to modify a configuration in the file: product.json to include the Microsoft marketplace URL.

Reason:
VSCodium uses its own marketplace called “Open VSX Registry”. Microsoft owns the VSCode marketplace and uses it exclusively in its software Visual Studio Code (Microsoft version); this marketplace is not set by default in VSCodium (Free/Libre Open Source Software).

Step by step:

Edit the /usr/share/codium/resources/app/product.json file is required. Steps:

  1. Close VSCodium, open a Terminal, and go to the folder where product.json is located: 
    cd /usr/share/codium/resources/app

    Choose one of two options: use a text editor or a Terminal app.

  2. (Option one) Open an editor and modify the product.json file.
    Open the file in an editor. 
    sudo nano product.json

    Search and modify to set these lines:

    "extensionsGallery": {
 "serviceUrl": "https://marketplace.visualstudio.com/_apis/public/gallery",
 "itemUrl": "https://marketplace.visualstudio.com/items",
 "extensionUrlTemplate": "https://www.vscode-unpkg.net/_gallery/{publisher}/{name}/latest"
}
  3. (Option two) The short way, you can use the sed command. 
    sudo cp product.json product.json.BACKUP-$(date '+%Y%m%d_%H%M%S')
sudo cp product.json product.json.TEMP
sudo sed -ne '\#serviceUrl#{a \ \ \ \ \"serviceUrl\": \"https:\/\/marketplace.visualstudio.com\/_apis\/public\/gallery\",' -e ';b };\#itemUrl#{a \ \ \ \ \"itemUrl\": \"https:\/\/marketplace.visualstudio.com\/items\",' -e ';b };\#extensionUrlTemplate#{a \ \ \ \ \"extensionUrlTemplate\": \"https:\/\/www.vscode-unpkg.net\/_gallery\/\{publisher\}\/\{name\}\/latest\"' -e ';b };p' /usr/share/codium/resources/app/product.json.TEMP |  sudo tee /usr/share/codium/resources/app/product.json >/dev/null
sudo rm product.json.TEMP
  4. Close and open again, VSCodium.

Additionally, some extensions request to modify the settings.json file. You can find it in the path (replace YourUsername with yours): /home/YourUsername/.config/VSCodium/User.

Source:

https://github.com/VSCodium/vscodium/blob/master/DOCS.md#extensions-marketplace
https://www.chrisatmachine.com/Neovim/22-vscodium-neovim/
https://www.reddit.com/r/vscode/comments/mqip0o/vs_codium_extentions_different_to_vs_code/
https://stackoverflow.com/questions/44057402/using-extensions-in-compiled-vscode