The Python SDK package is OK and has been better than managing raw requests to the REST endpoints. However, we need to have a type-safe and convenient way to interact with the REST API in non-Python environments plus there are a few straight up bugs in the way the Python SDK package queries certain REST endpoints. For example, it's not possible to create a group that allows users from all orgs to join...
My proposal is to simply generate and publish the OpenAPI spec files for as much of the APIs as possible. It's a widely accepted standard for documenting REST APIs and it would allow devs to use the SDK generator of their choice targeting the language of their choice. Easy win for flexibility when interacting with the ArcGIS online ecosystem.
I'm sure there are legacy reasons why it's not as simple as just generating and publishing the OpenAPI spec, but its absence feels like ESRI intentionally deprioritizing developer experience so would love to see this gap filled.