I have made several bindings in the past: Delphi-YAML, also CryptLex official Delphi support (was hired here). Also libipset binding for Ada (not public, unfortunatelly).
I propose creating a Delphi binding for existing native (C/C++) library, you can pick one, and I can estimate. Binding to C DLL is preferrable. Is it considered to be external library? Delphi-YAML is incorporating libyaml statically, but static linking is harder, porting to Embarcadero C++ requires more effort usually.