I am running Ubuntu 18.04 and I initially had several problems that I finally figured out how to solve (so far).  I thought some people might appreciate a synopsis of the issues I've experienced and my methods of solving them.

• The issue with Killer WiFi is well documented and I found that simply installing the latest linux firmware did the trick quite nicely.  In the link provided, be sure to examine the list of available firmware downloads. Be warned: they are not sorted in any clear order so you will need to carefully examine the dates posted to find the most current driver.
• Installing the latest Nvidia drivers was necessary to get my desktop GUI up and running.  I had to boot into the terminal and then follow the process detailed here.
• My biggest issue came with the advanced power management.  First, my XPS would randomly shut down either when running on battery or plugged in with the simple adapter but not when plugged in to the TB16 dock.  Second, booting up and shutting down was taking for ever and third, the fans would randomly come on at full blast under very light processing load.  I've listed all these issues in a single bullet point because the resolution was tied together.  After some investigation I found that by removing the "quiet splash" and adding "acpi_osi=Linux" to the GRUB_CMDLINE_LINUX_DEFAULT line both provided a very useful output of all the processes being run and resolved all my issues with boot and power management.

I'm bummed Project Sputnik only had 13 inch XPS laptops with native Ubuntu installed otherwise I might have gone that direction.  But things seem to be working well and I'm getting the performance I want.  I'm hopeful that new Linux kernels and maybe some firmware updates from Dell can help optimize my experience further.