You do not need to convert it to the first. If you export your xlsx sheet to a comma delimited file (csv), you can use the csv-table directive .
The great thing is that you only need to set up a table in your csv once, and whenever you update your xlsx sheet, just export it again to csv to the same place where your table used to be.
.. csv-table:: The contents of my xlsx sheet exported to mytable.csv
:widths: 15 40 20
:header: "Header 1", "Header 2", "Header 3"
:file: mytable.csv
. , .
, : file:. , , . , , csv.