The Open Book Environment (OBE) Dashboard
The Open Book Environment is a transparency dashboard about publishers, aimed at authors (and their funders) focussing on author fees, licensing, their policies on self-archiving, waiver and discount information, and any stated price justification. It is a very recent resource (2023) however, its longevity is unclear because it is a Google sheet maintained by two volunteer contributors. It also currently does not cover many publishers, but is being added to over time. It may be worth contacting the creators to ask about their long-term plans for the resource.