I want to add extra tags to the game activity node, specifically an intent filter to receive a command to open the activity from a web link…Thanks for your help.
You can add extra tags in Project Settings -> Android -> Extra Tags for UE4.GameActivity <activity> node. You can also do this by your own plugin written in Unreal Plugin Language. Samples how to do this you can find on my GitHub account: https://github.com/gameDNAstudio