This link is a little confusing because the top comment and much of the conversation is talking about the DTK which was based on the much older A12X CPU and not the M1.
As far as I can tell, the M1 does have virtualization support, Docker just isn't ported yet.
Update: Also, from Apple docs it seems like you won't be able to run emulation and virtualization in the same process. So you can run x86 Mac apps, but it's likely x86 Docker images will be out-of-reach.
Right, lots of confusion in this thread.
A12Z/DTK: HW does not support virtualization at all.
Apple M1 / New Apple Products: HW does support virtualization for ARM64 guests (both windows and linux demonstrated).
What about x86 software in the guestOS? Not with Rosetta. Instead, the guest OS will have to provide its own translation (such as windows/arm's current x86->arm64 or upcoming x86_64->arm64 feature). I'm not familiar if there is any usable high performance x86_64->arm translation available for linux.
Docker w/ arm images: needs some work to be able to work on mac/arm virtualization, but it's coming.
Docker w/ arm linux kernel + x86 userland images: Any translation solution would be found within the linux guestOS, not macOS. I don't know if any candidates exist. Maybe qemu?
Docker w/ full x86 image (incl. kernel): I don't think this is possible?
That could be something doing dynarec like box86, which is mindboggingly the only way to run (x86) Zoom on a arm7hf Linux atop a Raspberry Pi 4 (I tried it on a Pi3B: it works but it’s way too slow)