I’m not personally familiar with using Satscard + Nunchuck BUT I have emailed Coinkite support many many times and they have always been extremely helpful. I definitely recommend reaching out directly to them as well as Nunchuck.

When I was at Casa I would tell folks to respend the exact same UTXO but with a higher fee rate. Making sure you spend the same UTXO is critical. There are other factors that come into play, specifically if the transaction signaled RBF/if nodes are running their mempools with mempoolfullrbf, but trying to respend is a start.

Also do a little rain dance to hope for the mempool to calm down/the average fee rate to lower 😄