12+ hours of actual usage is doable on Apple Silicon, but it does depend on what your usage is. If you're compiling something 50% of the time then probably not. If you spend most time writing code and then testing the application after compiling? Yeah it'll last you 12.

I know that's not what OP has and it's not what they should get for Linux usage, but I've worked with 3 now (one personal, two at different jobs) and these things are the holy grail of battery life. First day on my M1 Air, taking it off the charger, 2 hours in it had used maybe 5% battery watching a udemy course and playing around in xcode.

So I think we should demand better of our laptops. I do believe AMD has done a lot, they had an entire generation where all they advertised was the increased power efficiency.