TopNotes.app Free
With TopNote, your notes stay pinned right where you need them, always in sight, never out of mind. 
Features:
- Always on top (CMD+SHIFT+T)
- No text formatting, cleans text on paste
- Save and Open .txt and .md files
- Minimal design
Devices supported:
- macOS 15 Sequoia
- macOS 14 Sonoma