Just FYI, when I tried to migrate from OC 10.0.6.1 using your official guide, it didn’t work. It tried to move to 12.0.4 and fail because apparently that path is not supported.
I tried then with 13.0.1 with the same result.
I moved to upgrading OC to 10.0.7 and then to 12.0.4 - same result. To 13.0.1 - same result.
What worked: OC 10.0.6.1 to NC 12.0.6, then NC updater to 13.0.1.
So far so good, but Rainloop seems to be missing functionality that was present in OC.