I’ve compared some frames myself and it does appear that the Blu-ray has more detail in many cases. Now as you say, this could be due to the heavy sharpening which creates the illusion of more detail.
In any case, I’d love to see some comparisons where the Blu-ray looks sharper, but is then matched by a heavily sharpened 4k77. I’d be glad to be proven wrong on this because it would be fascinating if a fan project has beat out an official release made from the best sources.