Most modern ides accomplish all of this with plugins, allowing it to support any language. Vscode, atom, jetbrains, eclipse. Even your example of Theia is just vscode with specific plugins running in the browser using docker.
There is a difference between you can add it yourself or it comes out of the box packaged as one thing. My idea was to pre-pack everything in docker, so you can tun it with one command and have all tools preinstalled. Example github.com/theia-ide/theia-apps/bl...
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