I found this too: BIOS guide - #11 by Kieran_Levin which suggests similarly. Hopefully they will consider supporting this as more than a one-off use feature.
I don’t mind if the battery is drained under full load, my understanding though is that the battery is just getting discharged once it reaches its charge threshold (rather than the laptop just running off the mains). I could be wrong though! For example running acpi -i, I can see “charging at zero rate” when I’m at the battery threshold. Maybe this is the “hybrid mode”, where it will just use the battery when needed.