Oppo A71s has ARM Mali T860 MP2 GPU. This is dual core GPU and the frequency is capped at 520 MHz.
No. Oppo A71s does not have the NFC support.
No. Oppo A71s does not have the hybrid sim card slot. Oppo A71s houses 2 dedicated MicroSD card slots and a dedicated MicroSD card slot.
Yes, Oppo A71s does have the OTG support.