You can get _actual_ excel. Google Sheets is also pretty decent. I don't think there's a libreoffice implementation, unfortunately.
>the shell
On Android, at least, actual shells are available. Most useful if you have root, but even without they're still shells, just ones without elevated permissions.
>or programming environment
There's, surprisingly, actually a few, though I don't think any are really competitive with x86 environments. There's plenty of good ssh clients if you're happy to remote somewhere else, certainly.
Notably, all of the above options I find basically intolerable on any touch device without an active stylus, and the latter two without a physical keyboard. Such devices certainly exist, though. A galaxy note with a bluetooth keyboard is surprisingly useful in a pinch, though you're always compromising with something that small.