The battery level isn't actually close to dying, in my case it just rapidly depletes from up to 40% when it's very cold. But that 40% remains intact seemingly with the screen off. Could be my phone also, but it has happened often enough that I wanted to solve it and thought this was an interesting approach.

For me, this was just a matter of convenience and not optimizing for most resilient or reliable solution. I do have backup plans for home entry.