Good luck, it would be fantastic if you can get it accepted as a mermaid alternative; it's much, much niceer than mermaid, both the visual result, and the language. I've used D2 heavily for a couple of years or so now. It's really fantastic. I hope you're paid product is healthy. Sequence diagrams are my most common diagram type by some way I think. And I seem to always use the sketch rendering over the last year.

While you're here, can I mention a feature request? I'd like to be able to put clickable hyperlinks into sequence diagram arrow labels (e.g. so I can link the message to where in the code it occurs).

Also, I'd like more control over vertical spacing in sequence diagrams, and perhaps the ability to define groups of columns (just visually grouped).