Success, after some dancing with USB drivers on Win10, the flashing did work out. Gee, windows is so bitchy with drivers 
Does anyone still have the original installer from Fairphone for the latest Android 10? According to
https://support.fairphone.com/hc/en-us/articles/360048139032#h_01GMTQS3F73GMK26E0RFAQ2SJE
that would be 8901.3.A.0136
Thanks 
Here?
Thank you! Alas, it contains only executables for Windows…
I am starting to wonder if the releases back then did have linux scripts at all? 
Other than that, for anyone interested: Yes, it does work but I find it somewhat laggy in general. Is it worth it? Probably not 
Still, nice to see other attempts at cell phones, looking forward to the next version 
PS: And from now on I keep my installers in the backup loop 
Some lovable people at Fairphone did consider it and added older final versions:
Awesome! 
PS: Grab it while you can 
Ubuntu Touch “Focal fossa” 20.04 is now available also for FP3 