NFC skimmer could not sweep the bitcoin because it requires the CVC/Pin from the physical card to generate the WIF. This information is not kept in the skimable data on the satscard. The CVC/Pin can be changed by the owner of the satscard as well, so even in the event the skimmer was able to see the physical card's CVC, they would not be able to sweep the funds.

I haven't used NFC CC + Nunchuk, but I would venture to say that any transactions initiated and signed via this method should be done in a secure place with the phone not connected to wifi (ie airplane mode) to reduce any potential risks