EUA can be applied to many different product categories including diagnostics (basically every single PCR and antigen test in the US up to very recently was initially released under EUA), therapeutics (for example the FDA granted an EUA on chloroquine for threatment of COVID), other medical devices (for example PPE) and vaccines.

The EUA rules for each category is different in how they differ from the categories baseline. For vaccines the gulf between EUA and full process was relatively small - the clinical dataset was basically equivalent.

I found this article to be a better summary of the differences between EUA and BLA (https://blog.petrieflom.law.harvard.edu/2021/06/15/whats-the...). I think you are right - the diagram from the OP is somewhat misleading.

There is absolutely nothing stopping a company from manufacturing whatever they want before they get a BLA - they just can't market it.

In real terms, it looks like the two big time savers was reducing long-term effects follow up from 6 months to 2 months, and well as probably an abbreviated review of manufacturing processes.