The last couple of days, I've encountered several situations where I wanted to quickly send content to my Kindle Paperwhite via the Amazon send to Kindle email service.

They support several formats (PDF, DOC, DOCX, TXT, RTF, HTM, HTML, PNG, GIF, JPG, JPEG, BMP, EPUB).

One piece of content I update weekly in Obsidian is in MD file format.

I converted that content to a graphic, to text, to PDF, and then to EPUB.  

I found the EPUB to be the best for me.

The conversion was simple: I cut and pasted the content in Obsidian to an open document in Google Docs and then "Download" (from the File menu) the EPUB version.

Once downloaded, I use Google Gmail to attach the EPUB to an email to my personalized Kindle email address.