nostr:npub1klw906w2f0lwfp7fle9al80fe77n7nmgnlyfh6s4he8gvn09t9dql0jmy2 is it always the same drive indicator? i.e. /dev/sdb or whatever? If so, you could use an if statement to see if that directory exists.
If the drive letters change, then you could use fstab to always mount it in the same directory. Then use an if statement to check to see if that directory has contents.