Is it really that simple? You can't have any active electronics - they would melt.
And the tungsten is touching the cobalt, with no air gap (i.e. to opportunity to harvest power from the electrons returning to the cobalt to neutralize charge).
Of course it's not simple, it's a very challenging project. But in terms of providing electrical power, if it's possible to have electronics that work at all then it would be possible to power them via beta decay. This is already an established technology in the form of "betavoltaics", which have powered existing devices (such as pace makers) in the past.
