I too am interested in the possibility of using the card for overdraft protection.
When the card showed up online today, I tried an internal transfer from card to checking. This works at another credit union i belong to and which will use the card for overdrafts, but it did not work at Alliant. The card simply didn't show as a source.
This is not a dispositive DP, though. Some possibilities:
Might have to request that link to be made (pretty sure I did @ my other CU, but it was a decade ago)
Might have to receive & activate card first (seems likely)
Even though card shows, it may actually not be fully finalized behind the scenes
Others I can't think of...
In this case (barring responses by anyone who knows), we're reduced to asking a CSR.