El gato video capture
Is there an update to el gato video capture for iOS 11?
Yes there is. Version 2.0.2 can be downloaded from here. Select Video Capture from the dropdown options on the left and then the download arrow appears.
Elgato states "Elgato Video Capture 2.0.2 will work on an Intel Mac with 10.11 or later".
I had version 2.0 when I upgraded my iMac from Mojave to Big Sur and it would not launch. I updated to 2.0.2 and it launches and works normally - or at least to the point of telling me to insert the Elgato Video Capture hardware into a USB port. I didn't progress beyond that. Version 2.0 is supposed to be 64-bit compliant but it didn't launch for me. I never had Catalina so I can't advise if it worked with that macOS.