The problem with using PostgreSQL was difficulty to make it work everywhere, we have at least one dev in each platform. I use the pure JS version of SQLite (sql.js in npm). The server is fairly small, having the bulk of the code in the client (SPA).

If it wasn't for the MySQL I had to implement after the SQLite work, I would say it's better to investigate the quickest way to configure a local Postgres DB. There are portable windows binaries.