xl imitates Microsoft Excel without shame but falls three letters short. Currently xl can only view very simple spreadsheets that are saved as tab-separated values.
If you have Excel you can save your spreadsheet as a .tsv file which xl can read. If you don't have Excel you can use xls2txt on Plan 9 to extract tab-separated values from an .xls file.
If necessary, convert the character set to UTF-8 using tcs.
xl is written in Lua and requires lua9.
% xl sheet
The VGA font which is the default on 9front does not look great. You will get a nicer looking sheet using Tahoma or Lucida Sans:
% font=/usr/k/lib/font/bit/tahoma/unicode.11.font xl sheet
% font=/lib/font/bit/lucidasans/unicode.7.font xl sheet