I’ve been using HA for a long time. I love that it is capable of aggregating all the data sources and orchestrating all the different sensors that are on the market. I haven’t used everything below, but I have used a lot of it and can give some pointers.
Instead of a Conbee II I would suggest the Sonoff Dongle. I reached a point when I had a lot of devices that the conbee couldn’t quite keep up.
I have smart bulbs from ikea, innr, linkind, Aldi. They all paired to the zigbee mesh pretty well. I also had some Osram ones that didn’t behave as relays so I took them out.
The BT sensors look nice, and I believe they integrate with HA well, but your HA needs to be in BT range for them to be able to communicate. You could also look at the Sonoff environment sensors. I use these tucked away in different rooms and they are great.
Cameras, the general advice is to make sure they support RTSP and ONVIF, with brands being Hikvision, Dahua or Amcrest. Everyone will say you should feed your cameras into a Network recorder first, with options often recommended being BlueIris, Frigate. I use Frigate.
Feel free to ask any follow up questions, I’ll do my best to guide.