Try Draw first. If the Kindle browser refuses drag-writing, use Dot or 2-Tap Line. Text mode places typed labels. Everything autosaves locally in this browser.
Kindle tips: Use a soft passive capacitive stylus, not a Kindle Scribe pen. If drawing feels laggy, switch to Dot or 2-Tap Line. Use the browser bookmark feature to save this page. Local saves live only in this browser/device, so use Export All occasionally if you care about the notes.