I doubt that by processing via HNO3 or AR, ruthenium get oxidized from metallic state. NurdRage has one video on YouTube where he attempted dissolution of Ru in AR with no luck - as expected and stated in literature. I have no experience myself on trying that. Yeah, if you already have some oxidized Ru, RuO2 or something like that, it could be possible from my perspective. But if it is just Ru metal, I think acid oxidation will be at least very sluggish and hardly proceeding.
And to the selling Ru dore... I am pessimistic about the outcome. Most of the PM buyers also struggle to come with fair prices for more "valued" PGMs like PtPdRh... We had no luck with attempted sell of Ir - we also had quite a bit of it, not tens of grams - more. But we did not found buyer here willing to buy it - they didn´t make a quotation on it. So for metals like Os and Ru, I don´t know. Same as selling Ni or Co, even in few hundred kilograms ammounts - no interst from bigger guys. With mixed NiCuSnPb concentrates, even for free, nobody was willing to take them even on ton scale.
So if you know about some Ir buyers, I am more than willing to talk about it