Intune integration with Kaspersky EDR Optimum: can it replace Defender for Business?

As far as I know, there is no integration. But that is true for pretty much all non MS security products. From a setup perspective, you can install Kaspersky agent on Intune manage devices, and have the alerts configured into Defender using a SIEM solution. I cannot comment on the use of Kaspersky itself as I have not worked with it and none of my customers are using it. Everything will come down to your security requirements and the budget for licensing. If you are approaching this purely from an administrative angle, then using Defender for Endpoint integrated with Intune is the way to go.