Developing apps not to be available in App Store

Yes. "App Store Connect" lets you distribute privately.

Is it an OSX app ?

If so, yes it is possible, for your private use.

Once app is created in XCode, you will see it in 'Products" in the left pane.

Option-drag the file to the desktop, and here you have the app on the Mac.

No need to go to Appstore connect.

Thank you donnist78. :-D

Thank you Claude31.

Yes this is an OSX app.

I just did what you metioned and it is indeed available as I was hoping.

Thanks again.