Isn't it sad that this is supposed to be a big deal?
The reality is - https://en.wikipedia.org/wiki/Boiling_frog - that the M1 Macs are now just one step away from becoming a closed system. With Apple ARM chips in the Mac, Apple can now easily lock the bootloaders of M1 Macs any time and make it a completely closed platform like the iPhones / iPads. And it is evident that Apple has been planning this for years:
1. The first few Intel Mac Minis allowed you some level of customisation of both the hardware (change RAM or HDD / SSD) and software (install other full featured OS).
2. Then came the Mac Minis with soldered RAM and SSD. You could no longer customise the hardware. Software was still customisable and you could still install other OSes. (Recall that Apple even offered free drivers for another OS, i.e. Windows).
3. The current generation of M1 Mini now doesn't allow you to customise both the hardware (everything is soldered) and the software. Technically you can install other OSes, but the reality is that currently only crippled versions of Linux and xBSD is available and practically the only full-featured OS available for it is macOS.
These are clear indicators of how Apple has been working slowly to lockdown the Mac platform like their ios platforms. The reason for this is simple - BigTech are increasingly moving towards selling everything as a service. Services are more profitable because it means they create recurring income (even after the device is sold) which means more profits. and Apple's successful business model for this, that earns them billions of dollars, is the closed-platform model that is evident on iPhones / iPads. (Moreover, such closed system also help in planned obsolescence). Obviously consumer rights go for a toss tough.