There is a lockdown as you cannot even boot linux anymore...

I guess that may count for you, but I mean lockdowns within the OS itself.

I don't care that I can't run Linux on my Mac. If I wanted to run Linux, I'd have different hardware.

You can change that on T2-based Intel Macs, at least, just like on Windows: https://support.apple.com/en-us/HT208330

Of course, Apple as an OEM does not support running non-Mac OSes, so virtualization should still be preferred for most use cases.

That's why I'm saying anymore. It was the case but it is no more possible with the new Apple Silicone laptop.

There’s no indication from Apple that they are intentionally not supporting this feature - just that it doesn’t exist right now. That said in practice I never use BootCamp because the driver support is always sub-par. It’s a much nicer experience to virtualize, especially now that most virtualization platforms offer native support for Apple’s virtualization libraries, such that installing third party kernel extensions are less necessary now than ever before. (I think the only ones I tend to install now are Tuxera NTFS support which tends to be really high quality. Apple should just buy Tuxera and ship them natively.)

I guess Microsoft will have to hurry up and build an ARM version of Windows so they can keep the rounding error number of BootCamp users satisfied.

An ARM version of Windows has existed for almost a decade. In fact it's running on quite a few laptops right now.

Since 1997 to be exact. WinCE ran on arm since time immemorial.

There is an ARM version of Windows 10 that runs on the Surface Pro X [1].

[1] https://www.microsoft.com/en-us/p/surface-pro-x/

Not only that, the first released version of NT on ARM was in 2012.

They had crappy code signing policies (only store apps on Windows RT tablet) which guaranteed poor adoption but that was a policy decision, not a technical one.

Catalina already broke a TON of legacy software and you cannot downgrade newer Macs to Mojave (at least not without some serious hacking efforts, and I know at least one person who tried and failed).

That's not true at all. You can use recovery mode to trivially revert back to the OS that was installed when the computer was purchased. If that's pre-Mojave then you can just upgrade back to Mojave afterwards.

What if the Mac had a newer OS than Mojave originally installed on it? That is how I interpreted the parent poster's comment. Given this interpretation, I'm don't think I'd have the expectation to be able to install an earlier OS.

With that interpretation, you'd be correct but I don't think you've ever been able to downgrade to something earlier than what it came with since the older OS wouldn't include the appropriate drivers or kexts to properly run the hardware.

So the choice is between running an older OS version that will go EOL sooner, or abandoning the ability to dual-boot? How is that OK?

ARM Macs can't run unsigned software.

Yes, but code signing can be ad-hoc, can be done automatically at build time, and doesn't require notarization. So it's basically just a way to ensure the binary has not been tampered with. I don't really see the problem here, as the code signing itself does not prevent any kind of code from running on macOS Big Sur.

With iOS, you have to be an Apple developer paying $99/yr to do ad-hoc signing, I'm guessing it's the same now for MacOS..

That's not true. Anyone with an Apple ID is able to sign software they build/binaries and install them on their iOS devices.

Although instead of lasting 1 year they only last 7 days, but there is no fee for a user to sign and install their own binaries.

My question was about MacOS and if similar behaviour exists there too with the M1 Macs.

To clarify iOS, so the app erases itself after 7 days? Or is it something like you can install an app for only 7 days after downloading/using Xcode?

To answer my own question, an ad-hoc signed iOS App will deactivate after 7 days unless you pay $99/yr. This behaviour is not present on Big Sur and likely M1 Macs, they can still run notarized and non-notarized apps: https://arstechnica.com/gadgets/2020/11/macos-11-0-big-sur-t...

If you can sign ad-hoc then there's no point, right? Just modify and re-sign.

Can be ad-hoc? For how long?

Cite?