Does anybody know how to estimate/calculate the total possible DPs within the range? Moreover, it is also possible that for some DP value there will not be any DPs.

For example, the minimum X-coordinate value I know is for private key 7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a0 and for 7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a1
Their X-coordinate has 90 leading zeros, so it is DP=90

Probably there are only 2 X-coordinates with 90 leading zeros, and no more.

Does anybody know some examples with more than 90 leading zeros in x-coordinate with known private keys?

PS. Example above is for (order-1)/2 and for (order-1)/2+1