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Unfortunately, it's not possible to increase the size of the nodes. And as an open source project, it's not likely that some sort of accessibility package will be added, any time soon. Not that I've heard of, anyway.
I know that someone made a children's version of Inkscape, called Kidscape (I think). I don't know if it might have oversized nodes, because I've never seen the program (although I think I should have a look at it one of these days....) but it seems reasonable that it might. However, I don't think it has all the features of the regular Inkscape.
If you know anything about programming, or you know someone who does, it might not be very hard to create a customized version of Inkscape though, which has bigger nodes. But it would take a really lot of work to eliminate double clicks and drags.
However, many, many mouse movements can be achieved through keyboard control. In Help menu > Keys and Mouse Ref links to this page
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