I would prefer it to be open-source, but at least the data format (markdown) is ubiquitous and stored wherever I want it to be stored.

Slightly off-topic, but do you use Proton's other products? If so, would you recommend any of them?

Readwise/Reader and that syncs to Obsidian. Been loving this combo.

I've been working through Solenoid by Mircea Cartarescu for the past few months. It's a monster of a book, and some of the writing is really great (very Kafka-esque). There's unfortunately a bit of awkward sex writing, too, but it hasn't pulled from the good writing by any means.