Is there a problem when I add my devices as grid source so I can see the consumption and prices?

[regal pollen]

Because adding them as device in the bottom single device row won't show it.

[dapper widget]

This isn't really what it should be used for

Grid consumption and export is preferably the absolute sum of all devices

That kinda data is used across other graphs so those may behave differently to reality, but if you don't have a total energy measurement it shouldn't really make a difference