Nice work! I am also a big fan of cloud run, since it has the best cost structure and is almost maintenance free. Also had similar thoughts before deciding on the tech stack, but I opted for a NoSql Database (RavenDB in my case). This was really a productivity boost compared to my previous projects with SQL databases. No more headache with ORM.

Regarding tests: I agree with you that you don't need 100% test coverage for some initial idea, but on the long run when the app becomes more complex (and it will, it always does) missing tests will slow you down a lot. You need at least to make sure that you write your code with testing in mind, so that you could add a simple unit test anytime in the future.