Looking to Rossi, although not taken seriously anymore, and even Soininen, recommending Nickel powder that seems to be optimized when particle size is in the range of 5 um, there would be a limited penetration depth possible.
One of the reasons why I'm reasonably confident that this idea could actually work even for thick&large objects is that when several months ago I reached out Holmlid on this matter by email, from the reply I received I got the impression that although the diffusion of the small clusters into the bulk hasn't been studied by his group there should be no limit to the diffusion depth, except for the time needed (as with regular hydrogen). So, my idea is that if this is true it might be possible to load any transition metal of any shape with these clusters - provided of course a large enough H(0) production.
Of course, the hard part here would be producing the H(0)...