My sqlite-utils command-line tool has a command for doing this:
[https://sqlite-utils.datasette.io/en/stable/cli.html#inserting-binary-data-from-files](https://sqlite-utils.datasette.io/en/stable/cli.html#inserting-binary-data-from-files)
sqlite-utils insert-files gifs.db images horse.png
I wrote more about that here: [https://simonwillison.net/2020/Jul/30/fun-binary-data-and-sqlite/](https://simonwillison.net/2020/Jul/30/fun-binary-data-and-sqlite/)