A new Wifi router would not be the best solution. If there’s an available conduit between the houses I would go for fiber install and get 2 ethernet to fiber adapters then get plug that into your current router or look at directional antenna assuming you have line of sight between the houses.
Only if the Iphone charger is a USB-C PD rated charger.
The Framework 16 has a 7840HS or 7940HS these are 35W to 54W TDP cpus. The battery is 85Whr.
Doing the math a minimum you get 1.57 to 2.57 hours using the TDP math. But maximum battery life will be a factor of little power the CPUs can run, (approx 5W) and the various items for the laptop systems, display bightness, , fans, M.2 drives, RAM. (approximately 5W to 10W). Crank up the power savings, reduce the brightness, turn off the Wifi / BT, and turn off not necessary programs.
Using that math you can probably get a maximum of 8.5 hours.
I think i shall pass on any WD based SSD for a while until the hardware faulted SSDs work themselves out of the market.
All rooms having dual cables pulled to each room with CAT7 wiring.