How about booting LEDE just one second?

How to Boot Linux in One Second - Jan Altenberg


It's a nice idea, but it will be a lot of work to implement.
First: Now, many scripts do checks on board identification to configure LEDE and initialize hardware properly, thus the application side consumes more time. Setting up LEDE as you suggest would require to completely overhaul these scripts and make every device specific in the image builder.

Second, the target devices in the video are more user-based devices that require to low-power consumption and immediate usage from start. IMHO for LEDE target devices this is not the case. Also, personally I don't think/mind that it take ~5 seconds - in my case on my LEDE powered devices - to boot up and run for longer periods (months/years) of time.
So, as the video illustrates: first look at the target audience and devices, than make an evaluated choice as 1-sec-boot makes it a whole lot less flexible when you have a wider range of devices to support as is in case of LEDE.

Great to have it will be a cool marketing feature "Instant boot"
But frankly I only reboot my routers when I am testing new stuff