Having an equivalent of Nitter and Invidious would be amazing! I would love to host an instance of this API, you should publish your code!

Apps like RedReader will be impossible to modify and use in a libre manner without a replacement API implementation like this.

> Having an equivalent of Nitter and Invidious would be amazing!

Something like https://teddit.net/ ?

Have you tried https://libreddit.de ? It can also be self-hosted

What will they do if many people do. Make the site inaccessible without signing in?

Even LinkedIn has not gone quite this far, usually the first page is viewable without logging in.