@Athena you ticked pretty much all my boxes, so I would probably start listing non-trans-specific things like UBI, free college, universal healthcare, etc.

I do have one, though: a single form that you fill out with your name and gender, and it propagates through federal and state agencies to change that information wherever it's incorrect, including your birth cert, social security, license, and passport. You can present this form at any private entity that stores your name and gender and they must honor it, quickly and completely, the first time. All for free and with only modest limitations, such as "you can't change your name and gender more than once a day."

I was going to include "starting when you're 18," but you said "should be reality," so I think we can do better. I think this should be possible independently at 14 (or earlier) without question, but whatever the barrier to entry is, a person should be able to at least petition for it without parental support. Those that need to petition for it should have free legal support in that process.