To be fair the UK probably could do OK outside the EU like Norway does, if we had a deal with the EU like Norway does, however the government don't want that. Similarly an independent Scotland could probably manage the same way , Denmark , Ireland, Holland do. I’d rather it didn't feel the need to, but I fear an independent Scotland inside the EU less than a UK hard or no deal Brexit for the UK.
As for the SNP , Ive done alright under them, voted for them, as a lot of English people here do, and so far not supported independence, its why they have been so successful , though the Labour implosion has helped, but you look where they've come from in the 20 years of Holyrood and it isn't down to Nationalism, especially the transfer of that success to Westminster where they used to do worse than in Scottish elections.