I know it’s not quite what you asked. But if you have a little DIY ability you could build a good UPS out of a 100ah LiFePO4 battery and inverter. I’ve seen a few youtube builds where the runtime beats out what you can get out of a regular UPS. And with less maintenance.

I think the implication is that they don’t use anything from any of those companies. I see icons for Bitwarden, Nextcloud, and Lemmy. So they’re probably a big selfhoster.