There are various methods to undervolt, and no, settings will not be consistent across all devices. All silicon is different and some will undervolt better than others.
I am by no means an expert at all. The only experience I have is messing with the “safe” curve optimizer undervolt on the Steam Deck. My first Steam Deck was able to undervolt a massive amount (think a couple hundred milivolts) which let it throttle the cpu much higher within the power budget and my fan was noticeably quieter with the same workloads. I blew up the motherboard in an unrelated accident, and my replacement unfortunately barely undervolts at all to the point it’s not really worth it. So it just depends on how lucky you are with the silicon library.
This software optimizer was done by using this tool:
Another method is modifying the bios. There is a tool called smokeless that can do that on AMD hardware, but it brings massive risk. If you go too low, it wont even POST and you would have to reflash the bios to get it back. I went as far as purchasing the bios flashing tools with a claw to grab on the bios chip to directly flash it in case something went wrong. But I never got the courage to try. Would rather play my steam deck instead of messing that much with it. And besides, the curve undervolt was pretty good.
As for the Framework16? I’m too busy using it and messing with it’s features that I haven’t had the want to try undervolting yet.