Alright, just to come back: Nikon Scan installed without problems on Win10 using the instructions from
https://www.shtengel.com/gleb/getting_nikon_coolscan_scanners_work_under_Win7.htm and the file from
https://lincolnscan.co.uk/Reference.html . I have not actually used it yet, but the scanner gets recognized.
I tried as well the VM XP route, which failed at least for my setup. I had let myself guid by Google's AI mode, isolating the device drivers from the Linux host and adding them to the XP system. Unfortunately, on my laptop the Firewire ExpressCard seems to hang on the same PCI bus as some other required devices and a complete isolation was impossible, so the VM did not start after handing over this PCI bus. On a different system this could still a way to go, but at least for me (Kubuntu with KVM/virtual machine manager + Windows 10 VM, on a Thinkpad T540p with Startech Firewire 400 ExpressCard) this wasn't working.
Which is fine, I have now Vuescan (in Linux) and Nikon Scan (in Win10), will compare how I like Nikon Scan or if I continue using Vuescan (raw scans and invertion in Darktable).