[0bit]

There is an offline version: https://www.diagrams.net (they had to change their name from draw.io recently). There is a download button right on the main page.

[yencabulator]

Which looks to be an Electron app, so there's a browser engine doing the rendering. Can I save a diagrams.net/drawio-desktop drawing into a file, and convert that file into an SVG in a lightweight batch job?

[flarg]

Yes

[rad_gruchalski]

That's awesome. Thank you.