In case you haven’t looked at this thread: Linux battery life tuning - it looks like idle usage for the current gen Framework can be tuned very low (~3W idle). Personally, I’m expecting that you could do the same with the 12th gen version.
There’s a lot you can tune to control temps and power usage via RAPL. Using thermald is the most common option but there’s also manual tuning you could do: Thermal management on Linux with RAPL limits
Alder Lake P does not appear to support >64GB of memory, but maybe ARK is wrong?: Intel Core i71260P Processor 18M Cache up to 4.70 GHz Product Specifications - if 96GB RAM is important for you, then you’ll probably want to confirm what will work for you w/ the laptop vendors directly.
For 3 x 1080p@60Hz displays, anything that supports a USB-C/DP MST adapter should work fine.
In terms of other options w/ potentially better battery life, I might look into the newly refreshed Tuxedo Pulse 15 Gen2 - it has a 91Wh battery and the Ryzen 5700U that should perform in the ballpark of the 1260P but much more efficiently. You can also use RyzenAdj to further improve power efficiency.