Je viens de voir sur MacRumors (le post date d'hier soir) que la dernière version du patch Micropatcher pour Big Sur fonctionne sur les Imacs Late 2009 and Mid 2010 and Mid 2011 sans modification hardware de la carte WIFI et BT. De plus , le "posteur" a fait la mise à jour à partir de Catalina sans problème 
. Il faut utiliser le Catalina Loader Opencore 0.6.3.
Il n'y a apparement que HandOff et Continuity qui ne fonctionne pas, ce qui n'est pas grave.
Notes:
- The stock WiFi and BT works properly patched, too. No HandOff and no Continuity, of course.
- AMD based systems offer 4K H.264 and 4K HEVC with Big Sur, again. After patching you have to boot OpenCore to get video output!! During and after basic installation you do not need it, weird....
- Nvidia based systems lack currently of iGPU based H.264 acceleration. No solution available!
- I have tested installing Big Sur over an existing Catalina installation. Right now everything looks fine. Possibly you wait with this approach unless you have known to be good backup and a working restore, too.
- The patcher assumes that owners of AMD cards and Kepler K610M, K1100M or K2100M use OpenCore to inject Whatevergreen, Lilu and the BacklightFixup. All these extensions will not be installed by the patcher automatically.
- Users of the ++ NVIDIA Kepler cards (like a K4100) get all these files installed automatically (namely Whatevergreen, Lilu and the BacklightFixup and the patched AppleGraphicsControl).
