I just started this game developing journey and already fell in love with pico's visuals.

I was reading this website to understand which one was the one for me and then i found out there's a new one coming out on march! What about it?

Why should we have all 3? I like the fact Picotron has more pixels, but I'm wandering if it may be too early... Documentation is not that deep and looks very hard to learn...

I suggest go with Pico-8 first while waiting Picotron to be more stable. Plus the limitations in p8 will make you more creative anyway, not to mention it's the currently most popular fantasy console between all three.