I did not find, in the documentation of the source code, a way to write booleans to cells.
Booleans show up as "TRUE" or "FALSE" in Excel -- depending on the language, it is "VRAI" or "FAUX" in French for example -- but are stored as a 0/1 value in the <c> XML element on the worksheet.xml
If I believe the source code of the Python XLSX library and the observation of existing Excel files, this is accomplished with the t="b" XML attribute in the <c> XML element: <c t="b">0</c> <c t="b">1</c>