Seem like currently Lightweight Render Pipeline and HD Render Pipeline are working as totally independent things. What I would like to see in future is the ability support Lightweight Render Pipeline and HD Render Pipeline development together easily. So, it will have the options to activate supporting both Render Pipeline. In material inspector it will have the Lightweight Render Pipeline and HD Render Pipeline settings put together for easy setup and other things that make it supports both Render Pipeline together seamlessly.
No, this will never happen by design, sorry. You have to stay with builtin if you want flexibility, otherwise SRP is about making a choice between one or the other for AAA performance. You can’t have both. This is mentioned a lot in various threads in this part of the forum so I am locking this as a duplicate. Thanks.