I once created an uri that allowed you to open files on the device. Which could open the excel... ofc this will not be in the same window, it will open the excel in excel.
Also you have to install the uri on every device that wants to use this feature and they ofc all have to have access to the shared drive.
Might not be the best solution, but with my sample it should be pretty easy to test out (if the tvs work with windows, no idea what a fire tv is)
Than you can see if the client is happy enough with it.