So it is possible to have a relative path instead of an absolute path, so your data sources continue to work as long as you keep the data source files in the same location as the worksheet that uses them.
The Excel user interface does not seem to have any way for changing the path though.
But you can edit the XLSX in a different way than with the UI. If you rename your XLSX file to .zip, you can extract it "as-if" it is a zip file (actually the excel workbook is a compressed file). Then in the extracted zip file, open the xl directory, and therein the file "connections.xml"
There you'll find the "sourceFile", you can change this and have it refer to the file name only.
Then, move the "connections.xml" back into the "zipped" excel file, and rename it back to XLSX.
Note just zipping the directory back and renaming it to XLSX won't do, because any zip command may use a variation of compression algorithms and options that won't always be compatible with microsoft excel...
So best is to move the "connections.xml" back into the already existing zip file (or even better, edit the file directly in the zip file, if your zip file handler allows it).
The ExcelFile.xlsx\xl\connections.xml file will look something like this:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<connections xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="xr16" xmlns:xr16="http://schemas.microsoft.com/office/spreadsheetml/2017/revision16"><connection id="1" xr16:uid="{F9606253-9C57-4B65-839A-8DEF5AAEA9F7}" keepAlive="1" name="ThisWorkbookDataModel" description="Data Model" type="5" refreshedVersion="6" minRefreshableVersion="5" background="1"><dbPr connection="Data Model Connection" command="Model" commandType="1"/><olapPr sendLocale="1" rowDrillCount="1000"/><extLst><ext uri="{DE250136-89BD-433C-8126-D09CA5730AF9}" xmlns:x15="http://schemas.microsoft.com/office/spreadsheetml/2010/11/main"><x15:connection id="" model="1"/></ext></extLst></connection><connection id="2" xr16:uid="{7FE915B8-2095-40EC-B6DC-A589A5A2D08D}" name="TimeTrackingUserEntryLog" type="103" refreshedVersion="6" minRefreshableVersion="5" refreshOnLoad="1" saveData="1"><extLst><ext uri="{DE250136-89BD-433C-8126-D09CA5730AF9}" xmlns:x15="http://schemas.microsoft.com/office/spreadsheetml/2010/11/main"><x15:connection id="TimeTrackingUserEntryLog" autoDelete="1"><x15:textPr prompt="0" sourceFile="C:\Dropbox\Wonderful\LifeorLive\TimeTrackingUserEntryLog.csv" tab="0" comma="1"><textFields count="5"><textField type="YMD"/><textField/><textField type="text"/><textField type="text"/><textField type="text"/></textFields></x15:textPr><x15:modelTextPr headers="1"/></x15:connection></ext></extLst></connection></connections>
where the C:\Dropbox etc is the path to my datasource which happens to be a csv file.
You can remove the entire path and just leave "datasourcefilename.csv" there.
Hope that helps! ^^