I've read Bun is just a wrapper, not actual Zig implementation anyway. Also, making a financial database in beta language that constantly changes and breaks is "really smart".
You can actually go and read the source yourself [1]. If Bun is "just a wrapper", then surely Node.js and Deno are too?
A wrapper over what?? Bun includes the JavaScriptCore engine for JS evaluation, but it's so much more.
As for financial database concerns, if you're serious about including a project like that in your system, you have thorough correctness and performance testing stages before you commit to it. And once it passes the hurdles, at that point what difference does it make if it's written in a beta language, or a bunch of shell scripts in a trench coat, or whatever.