Always Show / Always on Top for Text / Note / Checklist / Calendar
You can use the built-in Stickies.app in macOS. Go to Launchpad or in the Applications folder in Finder, and launch Stickies.app.

You can create a new note by pressing Command + n or selecting File → New Note from the Menu bar. To float a sticky note on top of all the other windows, press Option + Command + f or select Window → Float on Top from the Menu bar.

You can assign different colours to different notes and independently set them to float on top.