As you mention there are not hard limits. Regarding the number of views you can create, my understanding is that the limit should be the number of elements that you can create in a Derby database (the maximum table size is approximately 2**64)
Performance impact might occur from the client management. i.e. Visualizing millions of views graphically at the same time, might require a lot of memory. If you organize them in different databases, this will reduce the number of views to be displayed. Additionally, you can increse the Memory Heap size assigned to the VDP Administration Tool.
Also, Denodo 7.0 update 20190903 introduced several general enhancements in metadata management for some extreme scenarios. Optimizing the performance of metadata operations when dealing with very large views, with thousands of intermediate nodes and thousands of columns.
In my experience, I witnessed Denodo successfully managing thousands of views, with derived views with thousands of dependencies and thousands of columns, loading extremely complex tree views and execution traces.
Hope this helps!