@Abby Bangser thanks for the comments!
Looking at the referral IDP architecture, I believe all of the components are to some extent responsible for many of the big drivers like speed, cost, stability, security etc so whoever builds any IDP delivers on all of them to some extent. However, in a particular timeframe, some of these could be more important than others and for example "increasing speed of delivery by 50%" can become an objective for next year/quarter etc. From the business model point of view, both approaches could work - you may want to model a vision or the very next step like MVP.
"I thought this canvas was about the business case for them" - if you build a product and invite internal customers into it you must get ready for long-term funding for both enhancements and maintenance, so in general funding should cover PE team members so that they delivery on the biggest opportunities to internal customers while making the business working better rather then specific projects executed by PE.
A business model is fundamental to think through so that you keep the attention of the internal investors and build a long-term platform for decades - if you lose it situation is undesirable because it ends up with many teams using a platform that does not get funding which eventually starts to disturb rather than help.
Pirate metrics AARRR - acquisition, activation, retention, revenue, referral
Unfair advantage is actually a property of the team that builds the product and it is unfair because it is something that the team has that competitors don't have. Initially, I thought it did not make sense for PE, however, in big companies, there are aspiring teams/leaders beyond PE that want to build their own components of a platform without the right context and this can easily result in team local solution with closed paths for scaling to the entire company.