Xiaomi Smart Home - Alarm basic question

Hi all

I am quite new to Smart Homes and bought a Xiaomi Smart Home package (EU version) and several sensors from China.

Now what I want is to get rid of the xiaomi cloud. Now what to do? unfortunately there is a problem with the EU version as it is not unlocked to be used as a developer device and cannot be connected to a lot of software.

As what I have read here, it is possible to use the sensors with Home Assistant.

My first question is: Is it possible to use the Xiaomi Gateway as light and alarm tone somehow?
Or what alarm do you use instead of the Xiaomi Gateway?

What do I need as replacement of the gateway, which USB Stick?

Thanks a lot, i know beginners questions.