Just to clarify a point regarding Aqara region lock.

With Aqara product you have the possibility of using Mi App or Aqara App.

If you are using Mi App, the region of the hub has to match your region setting. Meaning if you buy a chinese hub you will need to set the region to China. So there is region lock.

But if you are using Aqara app, you are free to switch between regions (except Russia if I remember correctly). It will function essentially as NO region lock. Two things to be aware of: 1) EU region does not support automation because of legal requirement, 2) different region shows you different types of devices that you can add, that is why most people set it to China because they offer widest range of support for devices.

You will typically only use one app. I think it is not possible to have a hub added in both apps at the same time. Child devices will follow the hub according to the region. If you switch region, the hub will loose all child device bindings and you will need to add them again. But if you switch to one region, and then just switch back you will find all child devices are still there.

If you are using Homekit only, I recommend that you use Aqara app to help you add child devices. After that you don‘t use the apps anymore (except for firmware updates). Then essentially there is no region lock for you.

Aqara products are nice because they offer the lowest cost of entry to Homekit system. But you need to check that the device you want to buy actually support Homekit because not all Aqara branded products support Homekit.

Other bits about Aqara:

Currently all hubs are 2.4GHz only I think. Communication with child devices are not using the latest Zigbee protocol yet. But there is newer hub that will use Zigbee 3.0 protocol coming to market.

There are limit to the number of devices that can be controlled by a hub. The current hub can control 32 devices. You will need to add more hub for more devices. Newer one can control upto 128 devices.

Battery powered devices will not work as repeaters but most mains powered devices will be, for example, wall switches.

Last point for wall switches. In general (not just Aqara product), wall switches with neutral line will work more reliably simply due to the way they work. A lot of non-dimmable LED lights run into problems when used with wall switches without neutral line.