Slack is not owned by MSFT. Maybe you are thinking of Teams. Slack is owned by Salesforce.

The announcement blog post: https://devblogs.microsoft.com/typescript/typescript-native-port/

As I assume you’re not looking for FOSS-only solutions, you probably want to go with Jetbrains IDEs (IntelliJ). They are arguably the best IDEs around and have native Linux versions.

I assume you are mostly working with C/C++. I don’t have first experience with CLion but haven’t heard anything negative about it.