I was excited for Sync, installed it this morning and already uninstalled it because Connect is so much better. I am still curious about Boost, simply because I still use it for Reddit, but it will have to be really good to get me off of Connect.
Google used to respond to "OK Jarvis" and maybe a couple other things back when it was new. I haven't tried it in a long time to see if it works anymore though.
DDG has tracker protection that works like a VPN to protect your phone from trackers, it runs in the background no matter what app you are using.