LLVM's lit tool for testing files is the most successful testing DSL I've ever seen. It's used a decent number of projects outside of LLVM.
By contrast I don't see many folks using e.g. Cucumber these days.
LLMs have been really helpful for me porting some JS projects to TS.
Since the types are erased and annotations are optional, I can go gradually and safely with more minimal human oversight.
(I'm not sure if it'll significantly help robustness, but it's lovely for navigation.)
Reviewing some of my earliest web projects: they have a mix of Postgres, MySQL and Mongo.
These days I just use sqlite for all my personal projects. It's really good at my scale and makes deploying very easier.