WinMax2 seems able to run Qubes although different reports by different users. WinMax 2 is 10". There are versions with 64 GB RAM and that’s enough RAM to easily run Qubes. 16 GB is min, but uncomfortable. 32 GB+ is good. 64 GB makes things much easier.
GPD also made 8" conversion tablet with similar high specs. That would be extremely portable but the keyboard would be harder to use.
I had problems with WinMax2 and unusual things occurring with my system, including seeming like somehow I was being hacked or the system being controlled. I still have no understanding of why that happened but it has seemed to stop recently or perhaps just got less noisy. These issues could be caused by my network configuration. It is hard to know. The machines are very impressive and I am still impressed many months later. The only problem is I like the machine so much that I want to keep using it.
I really wish I were able to run heads or coreboot however and can’t do that.
The great thing about Framework is how long they can last, how they are so modular. But 12" is not that portable. WinMax2 is very portable. One-Netbook also makes small systems. You are looking for a UMPC.