Working on an Apple Notes clone, but everything is a local Markdown file.
Currently free, macOS (Silicon + Intel) and Windows. Has tags and priorities, can display many scientific syntaxes (mhchem, most TeX / LaTeX stuff, Excalidraw, PlantUML, Graphviz / DOT, Vega-Lite, and actual Markdown footnotes). Can show notes in vertical lanes like JIRA does. Free iCloud sync too. Still early alpha.
https://notesplus.io