Can you put another Sim into a Vodafone / Huawei GigaCube?

My idea would be to use a Sim from another provider eg O2 with unlimited data volume and to put it into the Gigacube as it would be much cheaper would it work?

This works because the GigaCube has no simlock, you just have to enter the access data in the GigaCube from the other provider.

Would the whole thing also work with a normal cell phone as a hotspot?

I don't know and I don't find anything about Google

Goes easily, I use it myself.