If you use you your own Telerik license and keep it up-to-date this is possible. DNN is not incompatible with Telerik, it only uses old (very old) libraries that go back to a time when there was an agreement between DNN and Telerik. As this agreement was cancelled a while ago, DNN (Corp.) had the permission to use the last version from the agreement, and also to patch the libraries when there are security issues. At this time, DNN Corp. had the full control over DNN, and some developers that took care of it - paid by DNN Corp.

As DNN went back to the community, there is not enough resources to keep this old version of Telerik alive, so there was an enourmous effort to remove it from the core.This is complete in DNN 9.11.0.

But there is no problem using Telerik with your own license. If you sell your extensions or publish them under an Open Source license, you need a developer's license and must not publish the closed source (i.e. Telerik) parts, but you are allowed to distribute the libraries needed for your modules etc.

Happy DNNing!
Michael

There might be some migration steps necessary, though. Because I think you'll need to first remove telerik from DNN and then add it back with your own license and code implementation. I'd expect you to have a version of your telerik modules that work before DNN telerik is removed and a version that only works after telerik is removed from DNN.