Oh believe me, I've spent a decent chunk of time exploring ways to make it practical, I haven't find any good way to pull it off for most doors in my house unfortunately :(
Maybe if I ever get to the point where I can have a new house built....
At his old company, my dad got a 500€ bonus because he wrote a MS Outlook macro to automate some specific email to excel and/or calendar data transfer (I think, been a while). As my dad is a huge TNG fan (initiating me into the fandom at a young age after literally naming me in part after his fav captain), the UI was obviously also based on LCARS.
I used a cheap WT32-SC01 Plus which integrates the screen with an esp32 package with breakouts for other useful things, like a speaker header, and flashed with openHASP
I never bothered to look I wasn't planning on battery power. I'm powering this off the existing doorbell transformer and wiring with AC to DC buck converter
Though from time to time I had it powered off my laptop USB and that only delivers 500ma so I can't imagine it'd be very much
Screen sleeps, but I wasn't originally going to keep it that way, but people just seem to instinctively tap it to wake and tap the ring button without issue so I've decided to leave it to extend the displays life
Even if it's not battery powered, I personally would be conscious of the energy inefficiency. But I would be fine with it going to sleep. I suppose it should also be possible to automatically wake it up if a person approaches, using a motion sensor.
Entryway is deeply recessed, so my front door is never really all that exposed to rain/snow/wind, but it seems fine with temperature swings between 20-75, but it wasn't online for the summer so I'm unsure how 85+ will be