This, Typst, etc etc are primarily typesetting systems for papers.
I would love alternatives to HTML or whatever, but I tried Typst too and it's very clear that the authors only really care about typesetting for papers and other long form prose. Stuff like forms, invoices, flyers, handouts, leaflets, business cards -- an afterthought, at best.
Edit: Actually I was thinking of Sile not Typst, but I think the same applies to Typst too. I didn't dig into Typst too much because it was commercial though.
Is there any reason why you can't use Typst for any of the stuff you mentioned? I can't see why you couldn't (except for interactive forms, which is already being worked on [1]. The pdf-writer low-level backend seems to have already implemented support for form fields, so it seems like a matter of time until it is implemented in Typst).
The online editor is commercial. They have a github repository releasing Typst under an Apache 2.0 license for free. I installed it using cargo (Rust), and don't use the online editor.
You can use typst locally and bypass the commercial bits. It is really easy to create different kinds of documents with it. I have been using it to create slides and handouts, and for that I already find it much easier to use than the alternatives.
My first "real" usecase for Typst was a poster [0], since it was much easier than doing it in LaTeX. It's missing some features, like wrapping around figures and flowing text between boxes, but TeX doesn't have the second either and both are planned in Typst.
I might be using Typst wrong, but it's like a visual programming environment. I guess I found my jsfiddle or other tools that other people use.
It's very satisfying to play with visualizations in Typst, especially since it updates the output so fast (instant for small projects).
You may be familiar already, but does paged.js fit your bill?
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> Stuff like forms, invoices, flyers, handouts, leaflets, business cards -- an afterthought, at best.
It is because you can typeset beautiful long text algorithmically and all these small forms like invoices and flyers are more graphical design than typesetting: you need to place many small elements precisely, not relative to each other but to the edges of the page / optical centers / etc. It is not very convenient without WYSIWYG. Possible, yes, but will require many trial-and-error when in WYSIWYG layout program can be done from first try.
Think about tabloids too: text, which wraps around non-rectangualr images, cut-outs, etc. Hard to do without seeing what you do, only with text and coordinates.
Edit: typo test → text.