Yeah we'll add that at some point.
It's a bit trickier than it seems because a lot of Obsidian configuration and app functionality is vault-specific. E.g. what theme should be used? What plugins should be available? Does autocomplete for [[links]] or properties do anything? Etc.
maybe you're overthinking it a little. You could make it of a default setup like the one you use for the sandbox, or some curated fast-loading one
VSCode opens single files outside of projects. What do they do? Personally I wouldn’t mind if it just defaulted to the settings of the last-used vault.