Just posting an update on this for all as I think there is much confusion around this and a few have come up against it.
The embassy replied to me that categorically no insurance is needed for single entry non-o and that a screenshot as above image should be uploaded to that form field of the application asking for $100k COVID insurance.
I had already done this at the advice of a comment below and my visa was approved without insurance of any kind this morning. So to be clear the London Embassy which is all I am commenting on about here is not asking for insurance of any kind for the single entry non-o visa.
that is great to know, I have submitted and see what they say - will for sure report back as I see others in the same predicament. Thank you all - greatly appreciated