Yours and other comment did reveal my analysis was flawed, thanks for that.
Re: the first two points, I really don't think so. I have a Nexus 5x that would kill the battery in around an hour if video chatting (to your point, it did get very very hot). There is also a recently revealed 'bug' in the NXP SoC being used by Librem themselves, who claimed it was killing the battery in an hour. I figure anything under 2 hours is fair game to be 'measured in minutes.'
Re:End of Year Librem 5 Update
by michaelmrose on Thursday January 10, 2019 @06:50PM
(#18879686)
How old is the battery in the nexus 5? It's a 5 year old phone at this point. Daily charging could have put it through 1000 or more charge cycles at this point.
I feel like if it were going all out at all times for no reason it would still last a few hours.
Also pretty sure this thing runs gtk apps NOT gnome which renders your analysis flawed.