AmigaOS 3.x is still common by people running emulators, and legacy hardware, and the Vampire V4. AmigaOS 4.x is still under active development for legacy hardware with PPC accellerators and "modern" PPC Amigas.
Then there's the open-source AROS and the commercial MorphOS too.
"It's complicated" with Amiga. There is a whole span from dedicated fans of "pure" legacy Amiga's with legacy expansions, via modern/new expansions, some of which replace so much of the functionality of the original that there's not much left that's actually used, via pure FPGA reimplementations, some which aims to significantly improve on the original, to new-ish PowerPC machines that can run AmigaOS 4.
So there's new hardware (that's not branded Amiga for legal reasons, but can run AmigaOS), old hardware, and everything in between.
Can't believe a modern Amiga is like $1700 for 2 GB of RAM (upgradable to 4 GB),when I just bought a Pi4 with 8 GB RAM, quad-core processor, and 128 GB micro SD card for like $150 with a case, fan, heat sinks, hdmi cables...etc.
That's because you're paying for an extremely small-run PowerPC machine for dedicated fans who absolutely want something that can run latest AmigaOS4.
For those who "just" want the cheapest way of running Amiga software, and don't have any particular reason for wanting one of the PPC boxes, an x86 PC with UAE (Amiga emulator) or AROS + UAE is a far cheaper option.
For those who wants something closer to the "classic" hardware, there are a number of FPGA based options with various degrees of advances over the classic hardware.
I think it's both for legacy Amiga users and users of modern Amigoid machines, such as the Vampire V4 and the AmigaONE line, that can run AmigaOS 3.x or 4.x.
AmigaOS 3.x is still common by people running emulators, and legacy hardware, and the Vampire V4. AmigaOS 4.x is still under active development for legacy hardware with PPC accellerators and "modern" PPC Amigas.
Then there's the open-source AROS and the commercial MorphOS too.
It's a mess.