[mothered]

1) On the tracking page, there's an option to indicate where to safe drop the item if no one is there at the time of the delivery (you can see the screenshot here of what it look like https://imgur.com/a/w4rjbFB). But once it is specified, it will show up on the tracking records that I choose to have it safe drop.

Given you've authorized to leave It at a safe place/location, It'll make you responsible for loss of goods.

As a last resort, I can always chargeback but I prefer to not do it as it's a lengthy process with my bank and there's still the proof that I choose to have it safe drop on the tracking if the merchant ever dispute it.

If you've chosen the safe place, your bank will side with the seller.

2) I don't do nothing and assume that the delivery guy  would simply leave it as safe drop which would help my case for DNA.

If It's left unattended or a signature Is requested, the DNA Is good to go.

My question: Based on the context above, if I choose to specify to safe drop can I still claim it and if it go to the P.O box I guess I won't be able to DNA it?

For the reason already mentioned, don't choose the safe place yourself.