@theghostoftomjoad
I just this moment discovered that the fellow Jayarava whom I mentioned is here on Mastodon, should you ever want a really really deep dive into the "Heart." He's done hundreds of pages of research and reporting on the topic, despite not actually even being a Mahayana guy. 😉 In case you're not already familiar with his work, the Heart topics can be found at
https://jayarava.blogspot.com/

A cheerful Solstice to you.