@Haioken Welcome to the Rockstor community and thanks for relaying / sharing your install experiences.
Yes we do suffer somewhat from the rather old kernel used by upstream CenOS install iso’s that Rockstor is based off, although there are plans to update to at least the latest version as we are still using a 1511 base:
And in that issue there are forum links to some who have had better results on newer hardware with 1611 and there is soon to be a 1708 which I’m hoping will be our next iso base as it is due our shortly. Just checked again and as yet not released. That issue also details a number of other forum threads indicating woes related to the older image base. I’ve just added this one to the list 
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Well done for persevering.
That should have been automatic (via our kickstart config), best to go with the defaults really as there is little actual customising of the installer as we assume a default install that is then ‘adjusted’ by the Rockstor programs once they take effect upon first install and reboot: ie we don’t deal with custom partitioning and assume the default presented by the installer as is. Not ideal and definitely work to be done there: starting most likely with the re-basing on the newest iso from CentOS.
If the dd transfers the partitions correctly and those partitions are ‘as default btrfs via installer’ then it may work (sort of) as forum member @snafu in the following forum thread:
helped with highlighting and testing the ‘strange’ partition naming used by nvme devices. But note the quote from the pull request that resulted:
“Please note that this patch does not address outstanding serial retrieval issues for nvme devices however @Snafu in the above referenced thread has developed a working set of udev rules towards the end of that thread.”
So as yet far from ideal but looks possible if you have enough camomile tea on hand.
As a result of the outstanding complexities of an nvme system disk install I’d consider defaulting to something simpler and easier to transfer from machine to machine (given your requirement for that given the install problems) such as a SanDisk Extreme USB 3.0 (now going up in price) or what looks like it’s successor (untested by me) “SanDisk Extreme Go USB 3.1” which in the former model’s case at least is essentially an SSD on a stick (with build in usb-sata bridge).
Thanks again for the feedback and maybe you would be best advised to take a work around for the time being and try our updated installer once it’s in place.