How to Create Accessible Pdfs From the Start

This is obviously absurd, and we don't know what you really mean. Probably billions of people use PDFs; I expect hundreds of millions use them regularly. I use them all the time, no problem, they work great.

PDFs are also a rare format which is preserved and functions reliably over time (decades) over systems (just about anything you can name). If I have a document I want to read 10-20 or more years in the future, PDF is the best bet.

The far superior presentation of professionally prepared PDFs - layout, typography, formatting, etc - makes a large difference for me when reading long texts. Also, the markup works very well and is also preserved - I can read markup from entirely different systems going back decades, and the annotation I make today I can read in 2050.

Thing is people want to do bunch of things they shouldn’t with PDF like automated parsing, editing or adding forms to it.

Ideally you should have an API or other structured data to pass around but of course life is more complicated. Like PDF is all you get because API would cost more than it makes sense to do bad job parsing PDF.

In my time using Typst, I found that Typst makes it possible/easy to make content even more abstract: write the content as a "data structure" and then present parts of it in various places around your document. For instance to list quantity/weight of a parts description in a parts index at the end.