So which broker? Like you I am based out of India so legally DGCX / US is no issue and it seems now Indian F&O is open for NRI/ OCI also
Issue is finding a single broker who offers all 3 countries and has a single platform which can be used!
Look on dgcx page there are brokers that offer DGCX,NSE and MCXhttp://www.dgcx.ae/index.php/en/partners. But the costs are very expensive for trading on DGCX. I ask some brokers what commis they have and its very expensive for me becose iam daytrader. commis are between 5 to 6 usd per side(included exchange and clearring fees) for RT 10 to 12 usd its huge when I compare to IB e-micro INR/USD futures on CME I would pay for the same contract(2 standart CME contract is 1 standart contract on DGCX and SGX 1,32usd for RT and on SGX 3,16 usd for RT.