Have two backups, the most recent data and everything else. Archive data to different databases, e.g. only have the most recent 6 months in a production OLTP database.

"daily test restore is infeasible for anything but toy projects. "

It probably depends on what you call "toy" project. If you work for Google, yes I think everything is a toy project, and you're right. I only worked for ~$200M ARR/1M DAU businesses and restoring was no problem. From your point working for a FAANG business it's a toy project I can see that. But there are many more "toy projects" of this kind than FAANG companies.

"10+TB backup for example, and thats a _tiny_ backup size for a b2c product."

Sure.