Thanks for the info. I chose QR this time, but I might take UA on following trips just to avoid the 2nd test at DEL. I believe I can just take the 2nd test at DEL and exit/transit to my next flight on UK to CCU, without waiting for results (unlike flights/passengers from South Africa, Brazil, and the UK, I think).
I have both OCI and a Business Visa (B2). I believe either is fine for visiting India. I believe tourist visa holders (T) cannot visit India at this time.
I have also gotten both Covid vaccinations, so let's hope they come out with a simplified requirement for those of us that have been vaccinated.