If Scotland wishes to be independent then it needs to leave the UK. That means ending the supremacy of UK law and taking back control of its own laws, borders, money and currency.
I am happy for Scotland to stay in our Union and glad they voted to do so. If they truly want to be independent then of course they are free to do so following a referendum. Its not the sort of thing we should expect to have votes on every couple of years, as you have to assume people made a longer term decision than that. Current polling shows Brexit has made little difference to the balance of opinion on independence. A new referendum would require a decisive shift in Scottish opinion to be worthwhile and for the SNP to risk it anyway.
The SNP got into a muddle over the currency during the recent independence referendum. Of course an independent Scotland cannot stay in sterling. Nor would Scotland be independent if it did manage to continue with the UK currency!
Now the SNP is in a big muddle over single or internal markets. It says it is crucial to stay in the EU internal market when this is not possible as we leave the EU. Yet the SNP recommends leaving the UK which similarly entails Scotland leaving the UK internal market which is a far bigger proportion of Scotland’s trade than the rest of the EU.
True nationalists would want out of both the EU and the UK, to take back control. The SNP always seem to be shuffling various kinds of dependence, not independence, with a strong bias to control from Brussels rather than London. It gets them into all sorts of contradictory arguments. The advantages of internal markets can be exaggerated. Getting out of an internal market which is also a currency union is both more difficult and more expensive than getting out of an internal market with different currencies.