And FWIW, adding glove liners usually makes my hands colder. My fingers need to touch and have a disposable heater in there. I did just find some boiled wool mittens that I'm going to try as liners in my Mercury mitts.
https://www.salewa.us/product/gloves/mittens-grey
So this is what I got - (in azalea, of course...) Tried them for the first time today. I actually just took out my packed out liners in my Mercury Mitts and used these instead. That results in the outer mitts being a little oversized, but not unusably so. Today was sunny and not exceptionally cold - started out a 24 degrees, up to about 34 in the afternoon, breezy. I typically would wear my mercury mitts with disposable heaters and it would be tolerable, but not comfortable. Today - I wouldn't say my hands were actually "warm", but they were very comfortable (with no heaters! Which normally is not something I would do unless temps were close to 40).
The real test will be when it's colder. I did realize that I can take the liners out of my Black Diamond Absolute Mitts - those have fluffy insulation in the shell itself as well as the liner and I THINK that they will be usable with the wool mitts as liners instead of the normal fluffy liners. (With the stock liners they are so much like boxing gloves that I can't grasp a ski pole....) Anyway - I'm definitely going to play around with it. I definitely liked the feel of the boiled wool on my hands. Haha, I did also think that I could use them as liners in some Astis mitts if I buy a pair, and that should equal pretty epic warmth!