1% CPU at idle

The subject is CPU at idle, which most people understand as being just Windows and a small App to measure CPU usage like the Task Manager.

Not the CPU usage when running Photoshop, indexing, temperature monitors, AV scans, various bits of additional hardware, etc.
Which is not idling, as you say "Again depends on what you have running."

CPU at idle vs CPU in use are two wholly different things. 1% means zilch in the computing world.

Helmut said:

It is about the display of numbers, number rounding to 1 digit to give a pleasing look.

If what you are looking at is the Task Manager then click on the 3 dots > Resource Monitor.
In the CPU section you will see CPU usage to 2 decimal places.
e.g. the Task Manager itself maybe 0.02% or something like that.

There is no way CPU usage can be 0%. That would only be the case if you removed/disconnected the battery and BIOS settings battery, and discharged any residual energy in capacitors.

My Laptops have always flickered around 0%-2% at idle.

Anything like 5%-20% would lead to checking what was wrong and/or poor settings somewhere.

Sorry, but in Task Manager or Resource Monitor, CPU usage is always rounded to nearest integer, I don't see decimals anywhere (screenshot below)

Unless you mean under the "Average CPU" column?