Over the years I have fitted so called smart devices for a variety of reasons, however the problem has been to work out what will do what, so I hope my experience will one help others, and two others can add their experiences.
It started in my late mothers house, lack of two way switching in bedrooms, room temperature control and switching off the extruder alarm before carers were due to visit, so we selected Energenie Mihome which we were told would integrate with Nest.
It worked well, the central heating control was good enough not to bother with Nest wall thermostat, the light switches worked without a neutral, it needed a hub, but only problem was only three time slots.
When we moved we took the above with us, and added to them, now some 3 years old we started to have problems.
Light bulbs (G9) stayed on dim when switched off, cured with load capacitor, and shimmer was noticed when on, cured in the end with illegal bulbs from internet (no marking of watts or lumen) but over next two years 3 out of 5 light switches failed, and also one socket, the energy monitors still being used today, and it worked with PC or Phone, and allowed use of cheap remotes, so still have a load working, but did not want to increase stock.
Next was Lidi, used zigbee, and got some bulbs, a remote, and impressed on how they worked, but Lidi when it's gone it's gone, so to increase needed internet, or other makes, so got Wiz, TPC, and TP-Link switches, so now three hubs, and every bulb seems to have diffrent features.
The dust and dawn features were not advertised, used on TP-Link (Tado) and works well, tried with TPC bulb, not really a success, not available with other bulbs and switches, but the WIZ has a fade in and out feature, so warns before switching off.
The relay worked well I built it into a lamp, where a neutral is available, but the Tado switch has batteries in the switch, so no problem with staying on dim of shimmer used with no neutral. But lamps I want to dim or change colour with, better with smart bulbs.
Think this is enough to start the ball rolling, now wait for others to add to or ask questions.