Postgres is awesome technology but for a lot of applications SQLite will do the job just fine. This gets you a single binary with zero external dependencies.
SQLite is not an equivalent to a standard networked database, as a developer you're supposed to see it as an enhanced data structure, like an array++. You wouldn't share an array between multiple processes (unless you know exactly what you're doing) so you wouldn't do the same for SQLite. If you really need multiple processes writing the same kind of data, maybe it should be partitioned into multiple independent files ?
Or for working with data in memory.
There's a whole world of software outside of saas crud
Look, it comes down to what you, the developer are comfortable with. If you know and are comfortable with running something like postgres in the cloud, then go for it.
Some of us prefer to not. Similarly, not all of us nuke the entire filesystem on every deploy :)
Litestream watches your SQLite database and then streams changes to a cloud storage provider (e.g., S3, Backblaze). You get the performance and simplicity of writing SQLite to the local filesystem, but it's syncing to the cloud. And the cool part is that you don't have to change any of your application code to do it - as far as your app is concerned, it's writing to a local SQLite file.
I wrote a little log uploading utility for my business that uses Litestream, and it's been fantastic.[1] It essentially carries around its data with it, so I can deploy my app to Heroku, blow away the instance and then launch it on fly.io, and it pops up with the exact same data.[2]
I'm currently in the process of rewriting an open-source AppEngine app to use SQLite + Litestream instead of Google Firestore.[2] It's such a relief to get away from all the complexity of GCP and Firestore and get back to simple SQLite.
[1] https://mtlynch.io/litestream/
[2] https://asciinema.org/a/I2HcYheYayeh7aHj23QSY9Vyf/embed?size...