Except for metallic and semimetallic oxides, is there any oxide (non-metallic oxide) which remains in the solid state at room temperature?
I think you are confusing metalloid with semimetal. These of course are squishy terms regardless and depend on what property you are looking at (physical or chemical behavior). But in general metalloid has more the connotation of small band gap semiconductor and semimetal the connotation of weak metal (small overlap of valence and conduction bands). So Si might be a metalloid but not a semimetal.
There are some weird halogen oxides that are liquids or unstable solids at near RT. Not sure if any meet your hurdle. And might need to be inside Pt or the like so as not to react with air or container.
Of course there are solid oxygen containing organic compounds that have only clear nonmetals in them. Maybe that is not an "oxide" though as they are molecular. (You could say the same of the halo-oxides I mentioned.)
Comment: I would prefer that this title be edited to include semimetal (or metalloid). It is annoying for the title to say something so different than the text of the question.