The last time I tried Codium, not being able to use Remote Development was a showstopper. Has the situation improved since then?

No, and don't expect it or Live Share to ever land[0]. None of the "Remote" extensions are FOSS, and they restrict usage to "validly licensed" copies of VS Code[1] – plus the server side code for it is closed source. So getting it into Codium would require a clean room implementation, essentially.

[0] https://github.com/VSCodium/vscodium/wiki/Extensions-Compati...]

[1] https://marketplace.visualstudio.com/items/ms-vscode-remote....

xaberus

The extension API proposals and RPC protocol are open sourced and the server code is just an electron-less version of the regular VSCode extension host (hence, remote extension host, REH). This is all part of the VSCode OSS release. What the proprietary extensions provide is integration. For example, the SSH variant automatically installs and launches an REH instance on the remote host and sets up port forwarding. If you are willing to start the instance and to forward ports yourself, you can use the tiny extension I wrote [1,2] (See the README how to enable the necessary extension proposals.). It allows you to connect to a local port you configure in the config. It is based on an example extension (vscode-test-resolver) in the OSS release that is used to test this functionality [3].

Microsoft is not really hiding any of this, so I am a little surprised, that nobody wrote a similar extension so far...

[1] https://open-vsx.org/extension/xaberus/remote-oss [2] https://github.com/xaberus/vscode-remote-oss [3] https://github.com/microsoft/vscode/tree/main/extensions/vsc...