As I am sure you are aware, some of the above components are already available (Native API + reentrant Python Gateway). Python PEX will become available with 2021.2, and DB-API and object access should follow soon, hopefully later this year.
Glad to hear this is resolved, but let me add that we are currently working on full support for DB-API:
https://www.python.org/dev/peps/pep-0249/
The idea is to have a one stop shop (Python SDK) where you'll be able to access IRIS from Python using the standard DB-API (relational), XEP/Binding (for objects) or Native API (globals), as well as having full access to Python from IRIS (via Python Gateway/PEX).
No, that functionality will be provided via DB-API