They don’t support sending messages over a serial / USB / network connection to say “battery is almost dead, shut down cleanly while you can” right? As far as I can tell, that’s the one key feature that a UPS has that a portable battery doesn’t. I took a look the other day and was amazed at how little UPSes have improved in the last few decades vs. everything else battery-related. At this point, I’d expect a consumer-grade UPS to have something like a Raspberry PI attached, and run a web server. I’d expect it to not just have a serial port for signaling, but to be able to run custom BASH scripts to send messages out to any attached device warning it about being on battery and keeping it up to date on the battery status.