There are food safe materials, although you want to post process some to remove porousness that can harbour bacteria.

Right. And a lunchbox would have to be close to the worst-case scenario for an item where 3D printing would actually be used.

I don't think it's meant to be a literal bento, the page shows photos with bolts and markers.

I've also thought that - just rechecked and found a useful link https://formlabs.com/uk/blog/guide-to-food-safe-3d-printing/

there is a large selection of food safe filaments like TPU

This is a well-worn topic, but FDM has many potential issues that make food-safe printing significantly challenging.

It is alas not enough to use a food-safe filament; you need a food-safe extruder drive and nozzle, and almost certainly will need print post-processing to make the printed item physically food-safe.

The issue with a lunchbox is acute because it has potential contact with individual items of food for hours at a time, on a regular basis. It's the perfect setup for bacterial growth in the layer lines -- close to the worst-case scenario.

There would be ways to mitigate that (liners etc.) but arguably even a food-safe filament would need considerable vapour smoothing or coating.

Hard TPUs up at the Shore 75D range would be tough enough for the job but they would scuff up while cleaning, and are resistant to coatings etc.

(Side note being that 75D TPU is quite capricious to print.)

Have you printed with TPU? It's very porous.

Everything is porous when printed.

blowtorch or acetone bath etc can make some nice pieces

i mostly stick to petg for everyday stuff tho