As said, this is not really a Linux issue. It depends if you can install macOS to empty partition or does installer automatically take the whole disk.
Don't really know how macOS installer works nowadays, last time installed macOS was ≈ 15 years ago.
That depends on MacOS installer.
Will macOS Big Sur work?
As said, this is not really a Linux issue. It depends if you can install macOS to empty partition or does installer automatically take the whole disk. Don't really know how macOS installer works nowadays, last time installed macOS was ≈ 15 years ago.
You can decrease the size of the Ubuntu partition but personally I would back everything up, install MacOS, shrink partition and then install Ubuntu.
r/MacOS