Is it? I don't know of any person using Duolingo or any other app to perfect their language. Most of them either learn from a uni course or something similar.

Although online, it is praised quite a lot.

I vibed the landing page so there are problems with it. Since it is my first app, I don't know how to write a copy. I will change it though. Thank you for your input.

I am aiming for a mobile app as well, but first I want to feed all the FSI course to the system before moving to a mobile app.

It is indeed LLM generated. I am certainly trying to change the landing page and make it more human. Thank you for you input though.

Would this be pluggable to any backend? Like say, Ruby on Rails or ASP.NET?

Triplit uses its own standalone server (similar to other database servers) which you can talk to via HTTP https://www.triplit.dev/docs/http-api

Is it built with pre-existing LLMs or did they created one from the ground up? With 21 million Seed A funding, an LLM powerful than GPT4 seems impossible. What am I missing?

Yeah seems like this could be replicated by another AI dev fairly easily.

Google launched another certificate.

How can one integrate it into his own android app?

To publish, just PUT/POST via your favorite HTTP library, or publish via intent (https://ntfy.sh/docs/subscribe/phone/#automation-apps).

And to subscribe, either use UnifiedPush (https://unifiedpush.org/), or use intents (see link above). Or, implement your own foreground service with WebSockets (just like the ntfy app does).