PlanMaker spreadsheets (.pmdx) can be easily exported as Excel spreadsheets (.xls, .xlsx) by using the default File ► Save as.. function in the program, which is pretty much what pmdx to excel conversion represent. Just keep in mind that some PlanMaker specific formatting might be lost with such export.
Unfortunately, Planmaker files are not supported in other spreadsheet software, so using PlanMaker is most likely your only viable option how to convert pmdx to excel.
Updated: June 26, 2023