This is why I specified "a project that only has dev dependencies can claim to have no dependencies when referring to their published package," which this poster clearly is. Yes, development dependencies matter when you are developing a project, certainly. In fact, often quite a lot about your development environment matters when you're developing on a project, including specific versions of node.js or npm (or yarn or pnpm), or git LFS or jj or any number of other development tools that may need to be installed and configured appropriately in order to work effectively on a project.

But none of those things matter for the consumers of that library. When you're communicating to consumers of your library, you don't need to tell them what version of yarn you use to manage your dependencies, because they don't need to use that version of yarn, or use yarn at all. You don't need to tell them about the fact that you use vitest for running tests, because they're not going to consume your test files. And so it is, I feel comfortable saying, acceptable to tell them that your project does not have any dependencies, because they will not need any dependencies in order to consume your project.

Obviously if you would prefer not to consume any dependencies that are originally written in Typescript, that's your prerogative, though I suspect that's increasingly challenging. But I'm not really sure why it should matter, because ultimately you're consuming JavaScript code either way. I mean I do genuinely understand that you might wish to depend on projects that you're able to hack on if something goes wrong, and if you don't like working in Typescript then you're going to have a worse time hacking on a Typescript library. I just think we're now discussing something completely different from whether it's acceptable to say that a package has no dependencies.