Several people who received the CrowdStrike offer found that the gift card didn't work, while others got an error saying the voucher had been canceled.
If they accepted a refund for the flights, it's probably too late unfortunately.
But for next time, airlines are required by law to rebook you in a timely manner. Even if it's on a competitor's flight. If they fail to do this, you can get home any way you choose then send them the invoice. If they refuse, small claims will force them to pay. Ideally record any conversations you have with them and keep all receipts.
If you're in the US, you can file a complaint with the DoT At this link here. It was set up recently :)
it's really Delta's job to at least cover the cost of the hotels/rentals for what is (basically) their fuck up. (that fuck up being using clowdstrike/MS.)