I aim to write standards compliant SVG, preferably SVG1.1 for backwards compatibility.
There is no resolution specified in SVG. Its a vector format using arbitrary units. It's down to the renderer to decide how to interpret unspecified units. Most browsers convert on 1 unspecified unit = 1 pixel. So browsers are useful for previewing svgs to get an idea of actual size for, in our case, of 64X64pixels. (You can specify units in pixels or points, but again, they are subject to interpretation by the renderer - this is where the confusion between 72dpi and 96dpi gets complicated: adobe and the rest of the world don't agree.)
I've not tested the conversion used in FreeCAD/Qt to create button images, cursors etc yet, but I'll be interested to see if it makes any difference whether I specify width & height or provide a viewBox definition. If I give viewBox definition, browsers will show the svg at maximum resolution, if I give width & height it will interpret the values as pixels.