Tangential: I wanted to embed a sane sandboxed scripting language in a node app and found… nothing. Only options were a completely broken node sub vm, half-broken js sandbox which isn’t maintained and slightly less half broken js sandbox?

Does everyone roll their own when they need to embed logic expressions in their yamls?

Lua is usually the embedded language of choice. If you are focused on security, you could check out the Roblox fork, Luau (https://github.com/Roblox/luau) where the creators took extra care to lock down the language on what scripts could do.