Reading Michal's Patreon posts from the last several months, it has become clear that his aim isn't an ARM-native AROS anymore but AROS/m68k running on his Emu68, which in turn is running directly on the ARM CPU without OS underneath.
"My initial idea was to run it as a seamless integration for legacy apps, with rest of the system running as an ARM code. However, limitations on the ARM side required by such approach, e.g. all parameters to system functions, hooks etc. passed through a fake m68k register frame, as well as variety of already available target architectures on AROS lead me to a conclusion, that one could run entire OS in such virtual machine, provided it is fast enough. And since my Emu68 seems to be indeed fast enough, it will run entire AROS, including hardware drivers. This gives us a stable ABI (the one from AmigaOS) and binary compatibility with OS-friendly software.
Sounds like a remarkably intense downgrade and a waste of resources.
And "ABI"? I assume he meant API.
Downgrade? I wouldn't say downgrade as it allows a single application binary for MC68k, ARM32 and AAarch64 systems.