This is useful. I'm still tinkering with Multipass VMs because I need the whole VM environment anyway and I'm on Sequoia. But I'd be interested if you did anything like that with Apple's container CLI instead; sooner or later I will have to upgrade to Tahoe because I want to play with the container CLI (and apfel).

it looks handy but ...

    sbx policy set-default open

just so the single pi sandbox can talk to localhost? ... this gives me some grave doubts about the rest of it being set up well.