I actually love the sidebar view that for example is used in the default energy dashboard. But it’s a bit small, a lot of text and entities get truncated. I would love to have it approximately 1,5 times the size it is now.
I was however surprised that you aren’t easily able to resize it, I tried it with custom css and with themes and I weren’t able to do it. (but maybe I am just too incapable)
It is possible to define a fixed width for a sidebar. I have several views with different presentations of a floorplan, and a sidebar (which has a different content on each view) has same user-defined width (which would be different by default). It is done by card-mod-theme.