You mentioned self hosting but if you want something without any lock in, there’s https://prose.sh/ — it open source, supports images, markdown, and you bring your own editor.

I’ve been a paying Kagi user for years and I don’t see why I would use this browser. The only selling point to me is WebKit and there are only projects that support that on Linux

Hmm it looks like they only tested KDE (KWin) compositor. I’d love to see how various Wayland server implementations impact performance since the compositor controls when it commits frames to the display controller.