Since there is quite some diversity in the OA books community, would love to hear more about the financial or business models that support Open Access books other than BPCs from publishers in countries across all corners of Europe and beyond.
OBP does a great job of being transparent about their publishing costs and about their revenue streams in their blog post of May 2020.
Are you a small or large publisher? What financial / business models are you using? And how do they scale, and do they need to? What lesson have your learnt? Please share here.