CGG I think the analysis and pathways given by @lbschenkel are a really nice way to try and explore solutions.
Knowing what the main issue was, also helps us think about non-google ways to solve that issue with mTLS, certificate pinning, etc... Banks found ways to secure their products, if we explore those solutions deeper we might be able to provide (at least at the theoretical level) nice alternatives for SERPRO and other apps that are also on the same path of depending on Google.
We can keep the good work of analysis and coming up with solution even though we don't expect adoption to happen.