Upgrading Storage1TB > 2 TB

Hi there I am running GETH and a Prysm validator on my NUC with DAppNode. The Disk is filled up with >80%, so I am currently looking into options how to upgrade the storage. Is there a recommended way how to do it? I wonder if the best way would be to go offline for 10 minutes, setup a whole new DAppNode, reeinstall the validator and sync it from scratch. Is there a better way how to do it? Also (even though rather a Prysm question), is 10 minutes enough to avoid getting slashed?

I only found this similar thread, but it wasn’t helpful to answer my questions.