Goodwin ink have just launched two asset packs the mega asset pack: https://goodwin-ink.itch.io/mega-asset-pack and the pixel asset pack: https://goodwin-ink.itch.io/free-pixel-art-asset-pack. They contain many props and assets that will be useful in a pixel art game.

Also if you are after some pixel art guns for your game check out: https://ellisjames20061.itch.io/pixel-art-gun-pack