VSCodium is an open source build of vscode, and this extension works well on it. However, it uses the command codium instead of code and the interactive rebase editor is not launching.
Could you add a branch to the appName switch:
https://github.com/eamodio/vscode-gitlens/blob/2b8a300703103b12ab90b17e1ad0a2d6c9ece1e6/src/commands/git/rebase.ts#L81-L91
case 'VSCodium':
editor = 'codium --wait --reuse-window';
break;
Thank you!