Actual number of pixels of display and maximum adressable pixels on canvas

I have 2 older smartphones.I use the oldest one to create my app.This phone has a pixel resolution of 720 x 1080.In portrait mode I can draw 360 points horizontally from zero to 360 [(0,y)-(360,y].At 360 the the last point has reached the end of the canvas/display (canvas width is set to "fill parent" and line width to 1).The same is true for my larger second phone:maximum number of addressable pixels also "only" 360.
I would like to know how App Inventor determines this maximum number(looks like its a constant for all phones? - at least that's my impression)
I uploaded the display informations of my smarties and as I wrote:different screen sizes but same number of maximum addressable pixels on canvas
Thanks to all for any replies

After loading an aia project into companion, get the Screen width and height from the corresponding blocks. These will give you the screen dimensions of an app inventor project. I believe the "low" resolution is to allow for older devices and APIs.

Wowh - you are right.I didn't know that I could get the current screen width via coding.Indeed the result was exactly 360.
I guess this will also be the case with my "larger" phone and I think - as you suggested that it might have something to do with APIs.The larger phone is a Huawei with Android 8 (can't ugrade to a higher version)
which is compared to my older Samsung (Android 6) extremely fast - so hardware wise the Huawei phone should have no problems with the dealing of higher numbers of pixel.
At least I now know what to look out for when drawing coodinates systems etc....
thanks TIMI2