That is cool.

What is a good way to use 3.35.4 on a system with a Debian version that comes with an older SQLite version?

Compiling it yourself from source is quite easy, you can find instruction here: https://www.sqlite.org/howtocompile.html

Here is an article from Julia Evans explaining it: https://jvns.ca/blog/2019/10/28/sqlite-is-really-easy-to-com...

Or if you are familiar with Docker, you can use a more recent Debian in a container and install sqlite inside it.

If you compile it yourself, how do security updates get to your system?

As for a more recent Debian version: The latest stable Debian has sqlite3 3.27.2 in the repos, so that is not an option.

Since sqlite is local to your application, you can just bundle a newer version.

Speaking generally, if the Debian version is the way to go, the easiest way is often to grab the source package from sid and build it. It's literally just one command. Sometimes new dependencies will cause trouble, in which case some manual tinkering is required.