#3300 contained various improvements for trimming/AOT in 6.0. This tracks remaining stuff to do.

• Array reader delegates (Reduce nullable and array reflection and code generation #3813). Note that we still use MakeGenericType so this won't actually work (but goes in the right direction).
• Enum handling - check if we need to annotate MapEnum or its non-generic counterpart, etc.
• Composite handling. This could be tricky because the user can map arbitrary .NET CLR types to POCOs at runtime. We should be able to offer an optional source generator that generates the appropriate stubs for reading/writing the user POCO; we'd still leave the current code since e.g. F# doesn't support source generators.
• Mark Npgsql as trimmable #4414