> I would be utterly happy if there were some program [...]
> to read and write document files in [...] excel.

https://blog.alb42.de/2019/06/02/its-a-leu/ can view and edit XLS, XLSX and ODS files.

Now also TCD (TurboCalc) files:
https://blog.alb42.de/2019/06/08/libre-turbocalc/

[ Edited by Andreas_Wolf 08.06.2019 - 22:27 ]