Home Assistant is one of the most known home automation solutions. it’s an open-source program written in python made to connect multiple smart devices API to make them work together. You can also connect your own devices.
The interface incorporated in home assistant is simple and basic. you can easily edit it. You can find a lot of themes in the community forum.
What can you control with a Home assistant?
I want to make my house smarter what should I do?
If you want to smarten your house, but you don’t want to spend a lot of money, you can use your old computer with proxmax or you can buy a raspberry