That i7-3840QM is a beast of a chip especially if your thermals can handle it. I am shopping for a new computer that’s what I compare all the newer cpus to.
I have been doing a little research myself with more restrictions. Have you looked at the dell precision 5560 or 5760? Some one checked the dell xps 15 9500 (2020) and found it is working with 4.1. The 5560 (2021) is the business line from dell that share the same chassis is the xps 15 but with slightly different internals. The main difference from the xps is that it has Linux support from dell and is certified to work with RHEL 8.4 which is some what similar to qubes. There might be limited sucess with the x1e or p1 which are direct competition. At least with dell you can get a machine in a couple of weeks instead of a couple of months with lenovo.