macOS Catalina installer freezes just after choosing disk
I found a fix for me.
Something told me that a disabled Spotlight might be the reason (I had similar issue long time ago and re-enabling Spotlight did the job).

If you have Spotlight disabled, then re-enable it using this in Terminal:

sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist


After installation you can disable it once again :) Hope it helps someone.

*Can also make this change in System Preferences > Spotlight > Privacy = Then drag and drop hdd into the window. To undo the action, just click on the hdd, and select the minus symbol. This did the trick for me.