for me it works the first 10 seconds then it starts lagging. i use an HTC U11 with Android 7.1 and Bluetooth 4.2 i think the Android Version is to high on older devices it works.
Both of the joy con's are without any lag for about 2 seconds. After that it start to lagging.
I have a HTC u11 with 4.2 Bluetooth.
I have downloaded the app Bluetooth auto connect and set the joy con's to HID but I got only 2 seconds lag free.