Especially if you are a one-man team.
I also wanted to ask how your personal project involves multiple men, but let's ask that later...
How strongly typed should it be between the layers?
What about the actual validation between the layers?
Do you monolithic, or multiple functions? Again, security between the pieces?
What about the database? How did NoSQL (MongoDB Atlas, for example), become RDBMS? (Where I see it as much safer and feature-rich, and aggregation frea)