If I understand the question correctly, you can export the file edited in obsidian as an excalidraw file via the “Excalidraw: Export Image” command, choosing Excalidraw. You can then import the file into Excalidraw by choosing Open and share it again.
Or you can simply select your entire drawing on obsidian with Ctrl A, copy it, and paste it into the drawing on Excalidraw, if you want the sharing link to remain the same.