Kivy/MD: "-m screen: droid2, portrait" is not emulating horizontal positioning for me on my phone very well ..?

Question

I've been writing my .py, .kv code on my PC and using python main.py -m screen:droid2,portrait to emulate a phone window size. I positioned it all OK, and built my APK (Google Colab, Buildozer).

On my phone the vertical positioning is OK, but the horizontal one is not. Its off by about 30 pixels. Plus my hand-drawn circle .png graphic is not sized right. Below you can see the difference. You can see my attempts in code to link the size of the .png graphic to another element.

Is there a way of linking the size of the graphic to an element to ensure its going to be near what I can see on my PC? And is there a better way than simply droid2,portrait to ensure correct positioning/scale on different phones? (I am keeping to pos_hint, size_hint as much as possible, rather than absolutes)

Button:
    id: MAmount_Button_Four
    theme_text_color: "Custom"
    pos_hint: {"center_x": .5, "center_y": .45}
    size_hint: .19,.09
    halign: "left"
    background_color: app.MUnderButton_Color
                on_press: app.MAmount_Four_Pressed()
Image:
    id: MAmount_Four_Image
    #allow_stretch: True
    #keep_ratio: True
    #size_hint: None,None
    size: MAmount_Button_Four.size[0]+dp(10),MAmount_Button_Four.size[1]+dp(10)
    source: 'LongButtonOutline_RightSize.png'
    pos_hint: {"center_x": .5, "center_y": .45}
Label:
    id: MAmount_Label_Four
    pos_hint: {"center_x": .5, "center_y": .45}
    text: app.MPercentage_Amount_Four
    theme_text_color: "Custom"
    font_size: "20sp"
    font_name: "Handwritten"
    color: app.MDeselected_Color