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SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
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logseq
A local-first, non-linear, outliner notebook for organizing and sharing your personal knowledge base. Use it to organize your todo list, to write your journals, or to record your unique life.
I think you could probably adapt Bookstack to your use case.
I'd also nominate TiddlyWiki.
I don't know very much about capacities.io, but by reading your description I think logseq (https://github.com/logseq/logseq) might be a good alternative.
What about Trilium Notes ?