Remember that Scotland is not 100% for independence, it's around 50/50 and it was actually 48/52 in favour of no to independence last year.I think that if the price of getting the Tories out was to commit to a 2nd Indyref - then Labour might cave
If Labour became pro-indy ref then that's 50% of the vote gone and the other 50% will be split with the SNP. If Labour stays neutral then they have access to 100% of the vote and at the moment they're far more likely to win more votes in Scotland than the Tories. They'll also likely win far more seats because they won't be battling the SNP on the independence ticket.
Labour would have to be completely stupid to commit to such a thing, plus it also poses troubling constitutional questions because how can Starmer form a government in the Queens name with a policy to perhaps dissolve the very country it governs?