Excel supported collaborative editing of binary excel files on SMB shares under windows NT, back in the 2000s.
Now, "supported" does not mean it was in any way good idea, or that it resembled how collaborative editing works in things like Google sheets or O365. Conflicts, deadlocks, etc were common - it's even why I built my first Rails app - we were given excel sheet and asked to do data entry on it over network from multiple machines, I didn't trust it despite a demo of it working and built a quick and dirty webapp.
Now, "supported" does not mean it was in any way good idea, or that it resembled how collaborative editing works in things like Google sheets or O365. Conflicts, deadlocks, etc were common - it's even why I built my first Rails app - we were given excel sheet and asked to do data entry on it over network from multiple machines, I didn't trust it despite a demo of it working and built a quick and dirty webapp.