I don't own a Canon 800D, so I can't test it. However, note that the gimbal can only support 800g (camera + battery + lens) centred. With the size, it could also be that the camera cannot be centred and/or that not all movements are possible, as the viewfinder could be in line.
Fsociety uses the gimbal with a 220D, but it is a bit smaller and lighter.
I would advise you to go for a bigger product or at least test it somewhere.

no