Not aimed at the poster... just a general observation.
I don't see Honda operating supply any different to Mercedes or any other manufacturers.
From my observations each customer has their own workspace liaison in the engine suppliers factory.
This can be increased depending on investment from the customer.
So the onus is on the customer to develop software if they feel it inadequate for their requirements.
As for lubrications, I would assume identical between supplied teams. For Mercedes supplied teams, this is a contractual stipulation as revealed by Williams and Force India. From a logistics perspective it makes sense as having 2 differing lubricants would actually be more expensive to the engine producers.
My view is the difference lies in software, and there are avenues for customers to increase development with investment.