Customizing node buttons

I am trying to customize node buttons, so they will appear exactly as my designer designed them (visual example is attached).

I would like to customize both the treeExpanderButton (appear at the bottom of the image), and the other buttons (appear on the right and left).
The customization includes changing the location of the buttons, so they will appear exactly on the shape border.
I can have an image file, or svg file, or which ever format of icon that you recommend to use.
Can you please specify if it’s doable, and if so, how should I imlement it?

Thanks in advance!

What is the SVG?

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