@wootwoot123 some artists do release these covers as textless images, but in their own tankoubon or compilation artbook. Examples: - Misaki Kurehito (AUN), Piromizu, Komori Kei (ExE), Magaki Ryouta - as artbooks; - Satou Kuuki (Unreal), Karasu, Toba Yuga, Oobayashi Mori (ANGEL Club), some Rakuten artists - in tanks. - Ishikei, Pija did include some covers in their works too.
I think, Seto Yuuki (MUJIN/Mugen Tensei), Urushihara Satoshi (Masyo), Nanao (ExE), Michiking (Anthurium), Hisasi, Doumou (various) and Yan-Yam (Penguin) did release something also? Can't confirm.