I say good on OP for putting themselves out there and keep pushing. We need young people to come up with great ideas and if that comes with them pointing out how young they are, I’m totally fine with it.
I'm saying this as someone who is relatively young, so keep that in mind.
The part where you build a demo/prototype showcasing if an idea works, I believe it should be much easier than before as long as you postpone understanding/deciphering the implementation. In those major ecosystems there are huge collections of single-purpose libraries doing a subset of what you want to do, all you need might just be a reasonable amount of python to string them together.
However, ensuring the correctness and actually deploying them for planet-scale mandates following a reasonable subset of "best practices" which is very overwhelming, but doable. People doesn't usually build planet-scale product 10-20 years ago.
I think this is specifically a big part of the problem. Not everything needs to be planet scale to be good. People didn't focus on being planet scale 10 years ago. 20 or so years Mark was worried about getting The Facebook available at one or two schools.
Worrying about getting things working for the world has made it way harder for us to get things working for indoviduals or small groups.