Apple HomeKit limits the number of Accessories a Thinka (or any other bridge) can control to 150. Or 149 if you include Thinka itself.

However an accessories can be a lamp that has 4 lightbulbs, that can be switched and dimmed. In this case, one accessory (the lamp) has 4 services (the bulbs) that have 4 group addresses (on/off set and listen, dim set and listen). So in this case 1 accessory can have 1 * 4 * 4 = 16 group addresses. So the limit of 150 accessories in practice means you can have a multitude of group addresses.

Most accessories will have two group addresses, but you could combine multiple services into 1 accessory. The Home app shows services, not accessories. Services in the same accessories will always be in the same room though. It just depends on how you define an accessory.

If you still need to control more accessories, you can use multiple Thinka's in the same network.

For more on HomeKit see our article.