Scotland at least mulled independence quite seriously pre-Brexit, and one of the strongest arguments against which the UK advanced was that in leaving the UK Scotland would also leave the EU. The EU presidency, at the time held by Spain which was also concerned about its own independantist movement, supported that argument.

Then the UK voted for Brexit. Scotland and Northern Ireland voted against but England voted for it, and it outweighs both, so the UK left, dragging Scotland and Northern Ireland along and out of the EU. Neither were hugely amused.

So to answer your question, the Venn would likely be somewhat disjoint. That's a simple summary of a messy bag of thorns, though, so the details are likely way more nuanced.

> what's the venn diagram of folks who support this, and who supported Brexit?

Unfortunately, in the long run folks don't count, they do as they're told sooner or later - when money talks it's only a matter of time. It might be hard to accept this but without understanding it, it'll never change.