I'm not sure I understand why PostgreSQL would be "overkill" for something? It's very easy to set up and operate, almost anyone in the industry either knows it or they should be willing to learn it as it's the de facto standard for almost any modern company using an SQL database.

Also it's very easy to buy PostgreSQL from various DBaaS providers. There's a docker one liner to set it up on any development machine and you need to run it just once.

Sure, SQLite is a little bit easier but it's so much less powerful as a database. Why not just go to Postgres directly and leave SQLite for what it's intended: embedded programming like mobile apps or in-car entertainment systems etc.