Not sure if this is the right place to ask about this, but I was wondering if it's still possible to unlock the sphinx trinket items even after unlocking the sphinx battle challenger? I was foolish and didn't even think about whether or not unlocking the challenger might render the other things unavailable.

Nope, the items from the trinkets are completey unrelated to the challenger :)

ok thanks! I was starting to get worried that i hecked up and didn't think this through before unlocking the sphinx, as i completely forgot to complete the winter trinket riddle before doing that.