Groups inside of groups are currently not supported (I need to fix the possibility to drag them into each other 
). I plan to add support for them at some point.
Bluetooth toggle events are currently not available, however there is a very lightweight way to check the bluetooth connection state for a specific device, see this: Compact AirPods widget with User-Friendly Setup
I'm currently adding more notification based triggers, bluetooth and wifi are good candidates. (Wifi is already possible using a conditional activation group, but I'll make it a bit easier soon)
If you are not on the latest alpha I'd also try that before making changes - there have been some good performance improvements lately.