I have office insider subscription and developed a sample for custom function and published in iis and it is working fine in my excel as I have office insider subscription.
Other than me, will the other end users who use the excel without office insider be able to access this custom function?
the feature is still in developer preview and will be enabled for Excel desktop users when it becomes generally available. We're still working on it.
To answer your question, you can sideload your custom function sample on Excel Online: https://learn.microsoft.com/en-us/office/dev/add-ins/testing/sideload-office-add-ins-for-testing
thanks!
