When a new OS is distributed one of the first questions asked is what apps work and which are broken. I installed Big Sur on a MacBook Air, and did a quick test of the soft that I used for photo and video work, mostly open source and a few free. These are the apps tested (opening, some basic stuff, saving and closing the app):
This are the ones that passed my very basic testing:
darktable 3.2.1 and dev 3.3+1404
DaVinci Resolve 16.2.7
Shutter Encoder 14.3
Libre Office dev 220.127.116.11
And these the ones that I could not open:
Digikam 7.1 and 7.2 beta
Hopefully the situation will evolve for these two apps in the future.
Libre Office 18.104.22.168 did not open but the latest dev version 22.214.171.124 works OK. And very promising, darktable is running faster on Big Sur than it was on Mojave.
Hope this basic info helps the few Mac users in this community to update, or not, to Big Sur. And if there is interest in the crash reports I can add those for ART and Digikam.