I have seen from the razer Synapse 3 demo on the CES 2019 that the synchronisation between multiple third-party devices can be possible currently:
I am using the following softwares: MSI Mystic Light Ver 18.104.22.168
Thermaltake TT RGB Plus Ver 1.2.6
Synapse Ver 22.214.171.12405
All are running on Windows 10 64Bits Ver 1809 and all are the latest versions you can download officially
However the synchronisation doesn't work.
I'm wondering if they've used specific beta versions to make the demo functional at CES or maybe i'm missing something to make it work?