How many % of UEs support UE based ANR?

There are many UEs supporting 5G->LTE ANR.
Basically UE should have below capabilities.

MeasAndMobParametersCommon - eventB-MeasAndReport
handoverLTE-EPC
eutra-CGI-Reporting
mac-ParametersXDD-Diff  longDRX-Cycle

It’s not same. You case is ENDC case.

What @onkar.ghatpande is asking is NR SA to 4G SA ANR.