Hey I experienced the same thing this morning (Pixel 8, stable with security preview releases enabled). I'm familiar with some of the workarounds for the standard issue of not enough charge. This time, it seems a partial OTA update was applied while bootlooping with not enough battery.
I do recall fixing this by setting the active bootslot via an adb shell in recovery in Android 15 when a partial OTA applied during this bootloop charging state. But if I understand correctly, that's been hardened in Android 16, so no longer able to do.
My device was actually able to boot no problem, but as soon as I tried to unlock, it froze to which I attributed to this failed update. I tried sideloading the OTA in recovery, but there was a timestamp mismatch for the release. I let it boot again and just sit in the lockscreen where it was functional. And luckily my system image wasn't fully dead, so to my surprise, after waiting 40 minutes or so in the lockscreen, it unlocked successfully without freezing. It seems the snapshot merge was able to complete in the background.
I've now disabled security preview builds in the hope if I encounter the issue again, I can quickly sideload the latest OTA release. I'm not sure if any of that is of help, but I hope you can find a fix!