I don’t know if that kind of setup is legal in the UK. It’s actually fairly common in the US in those jurisdictions that allow it.
But there are some jurisdictions that are concerned if the fitting is wired to be always hot that then someone who needed to do repair work on the fitting or replace it might think it had been turned off at the wall switch and injure themselves.
If it is legal to wire the bulbs as always on in your jurisdiction, though, understand that if for any reason your home automation system is not working you will have no way to turn those lights on or off.
That’s why personally I prefer the set ups where you put a case over the existing switch and then put the controller on top of it. That way the original switch is still available if needed. But different people go with different things in this situation.