TiddlyWiki really is one of the cleverest apps I've ever run across, but I'm not much of a JS programmer, so it's got a bit of a learning curve if you want to hack on it. It's pretty easy to use right out of the box if you don't want to hack on it, though, and I'm giving some thought to moving most of the data I've collected in OneNote to TiddlyWiki to escape Microsoft's clutches after I've finally disentangled myself from Google... One thing I love is that TiddlyWikis I built 20 years ago (granted, they were simpler then) are still perfectly usable today.
My perfect data keeper might be something of a mashup between TiddlyWiki and a JuPyteR notebook.
I run a local CGI server and that allows me to make all kinds of customizations in the language I want (most languages support local CGI servers). The querying capabilities of TiddlyWiki make it a nice database.
Image/file upload
Web clipper (singlefile is great)
OCR (Tesseract has done what I need, not sure how that compares to Evernote)
Basic task management
Customizable dashboard
Tagging and excellent search (these are Evernote's bread and butter)
WYSIWYG editing
Templates
Integrations
And it would be really nice if it could do math, which would be an advantage over Evernote.
It's possible some of this is already implemented; I only gave your page a short look.