I get them from this github page:
github.com/SilentNightSound/SR-Model-Importer-Assets/tree/main/PlayerCharacterData

Unfortunately for the rest you either need to look/ask around or make your own model dumps directly from the game. I've asked for one privately after failing to extract it myself (I WAS TRYING ALL DAY...), since it Boss Aven isn't available anywhere publicly, I don't think, but feel free to DM me for files!