It's all client side -- someone (maybe me!) would spin up openkeychron from an old saved copy of the webpage and we'd be back in business in a day. Right now the keychron-hosted solution is fine -- no accounts or anything crazy -- so there's no impetus.
EDIT: turns out that my keychron, at least, is compatible with QMK/VIA and there are already open source alternatives [1] that do the job.
Web-based software is easy to extract (singlefile), preserve (webarchive), or even rebuild during its lifespan.
Desktop software is way less reliable than you think – I have a few Akai keyboards I can't configure because they don't work on my Mac already, not to mention how hard it was at least finding this executable for more than decade old keyboard.
