Not sure about 8-12oz.
From my research, the lightest pull in single stage, as advertised, is 1.5lbs by Jard. JP Rifles is 3-3.5lbs single stage as advertised.
For the Geiselle and Jewell, both 2 stage trigger designs, both stages can be adjusted. On the Geiselle, the 2nd stage can be in oz (4-14oz I think). You may also be able to swap the stages, and make the 2nd stage heavier than the 1st, but I am not sure.
Most of the others have fixed pull weight. But you can pick the weight.
For a 1911, which is, of course, single stage semi-auto, 2.25lbs is pretty light but not uncommon in a hopped up custom. Not sure a lightweight pull in semi-auto has been done in a production/aftermarket trigger. Especially with the recoil of a rifle cartridge.
A lightweight "speed" hammer with some lighter weight springs for reducing lock time is great. To be sure, the shape of the hammer, sear, trigger need to be addressed for smoothness, etc. of any of these triggers.
Reading on many sites, including ARF.com, none of these aftermarket triggers are reliable as the factory military basic trigger. If your rifle is dual-purpose, you may want to have 2 triggers.
I run a loading block when I am at the range, so I can run springs that are light enough to cause doubling or tripling in my case, so they are easily swapped out with heavier springs using anti-walk pins in the trigger and hammer when I head to the hunting lease.
The market is really appealing to the "tactical" crowd that want more precision.
For my DPMS trigger, the distance travelled is quite large and the let-off is inconsistent. An expert, such as Bill Springfield, will shape the hardware to improve on this. I have emailed Bill before, and he was great. I was before unable to part with my rifle long enough, but since he is selling them outright, I will have to decide to go that route or maybe Big Al has a good price.
Big Al: didn't see how to send a message or your email. Here is mine: F o r n e y R i d e r @gmail.com.