I enjoyed reading this and gave it an upvote.

I also tried building my own programming language, and I think the difficulty depends a lot on how far you want to take it.

At first, when I used C as the transpiler target, it felt relatively manageable. But once I tried to support a different backend, the difficulty increased dramatically. It is now a project I work on seriously with LLMs, and my impression is that making a language is both easier than expected and harder than expected.