21Shares has filed for a Dogecoin ETF with the SEC, aiming to provide institutional investors with exposure to DOGE.The ETF will directly hold Dogecoin, with Coinbase Custody managing the assets and tracking its price.If approved, this could be a significant milestone for memecoins in mainstream finance, opening doors for future products.The Dogecoin ETF filing by 21Shares may mark a shift in perception by institutional investors towards the memecoin sector.