Looks like according to those that make decisions for you, Unreals users will not be allowed to use these bushes on the basis they are not sufficient variety… TBH, these are FBX models, materials and standard textures, you can pick up both Volumes on the Unity Asset Store and they will port in without issue (except the materials).
The same can be said for all the models I create and have been selling for over a decade. Most can be found on the Unity Asset Store, as long as they are not scripted objects like the Security Systems.