How to configure different editors for in-ide and in-terminal usage?

Question

I have vscode running in a Flatpak sandbox.

• I configured git config --global core.editor "codium -w", which works from within vscode. When I use git in a stand-alone terminal it can't find the editor codium because it's not available on the native system.

• I configured git config --global core.editor "subl -w" , which works from the terminal. When I use git from inside vscode it can't find the editor

• I configured git config --global core.editor "flatpak run com.vscodium.codium -w", which has the same problem as above, with the addition that it inconveniently brings the first window of vscode to the front instead of the most recently used window.

Does git have a way to make it that it can both be used from the terminal and from within a flatpak?

I have some suspicions, because I installed a git plugin, git-subtree, which is only available from the terminal, while trying to invoke it from within vscode complains that git: 'subtree' is not a git command. git --version gives different results in the terminal and in vscode. It just seems that they both use the same config location. Maybe my question can be reformulated as, "how to set a different config location for git?" or even "how to alias <the config file> to a different physical file, for flatpak?"

[Edit] Some additional information:

• The flatpak has full filesystem access
• echo $HOME contains the same in both cases