There are possibly several options available. From a cursory search, native Mac applications include:

• Nebulosity
• Keith's Image Stacker
• PixInsight (cross-platform)
• Starry Landscape Stacker

If none of the Mac native applications do what you want, you're probably going to have to consider somehow running Windows programs. Your question rules out running Windows in a virtual machine, but you could also try the following options:

• Wine: A not-emulator that provides a Windows-to-POSIX API compatibility layer to run (some) Windows applications on Linux and Mac systems. Not as reliable as a decent Windows VM, but requires less disk space and resources. Not all Windows applications will run under Wine.

• Install Windows via BootCamp on your Mac, and run Windows natively. Of course, this requires a full installation of Windows on your hard drive (just like a Windows VM would). But this is the best-supported and highest-performing option of the three choices (VM; Wine; BootCamp) for running Windows applications on a Mac.

If none of the native Mac programs work, try some Windows programs under Wine. Reportedly, Deep Sky Stacker and Registax work under Wine. If they don't work, and you can't find Mac options, then you're going to have to resort to running Windows in BootCamp, if you don't want to run a Windows VM.

See also:

• Best opensource/ free stacking software for mac for astrophotography
• Macintosh Computers in Amateur Astronomy, an absolute treasure trove for astronomy on Macs, by David Illig.
• Astrophotography with Mac OS X (cafuego.net)
• Stacking for Mac Users, (cloudynights.com forums)