

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.
Can you use git without a forge? Sure. As long as you don’t give a hoot about the entry barrier. But for any open source project were you want to encourage contribution you better have a nice presence on a forge.