The platform documentation does not provide information on this.
But I know that there are some maximum dimensions so that the image can be conveniently rendered in the wallet.
I suppose that the standard 512 x 512 is ok.
But does anyone know what is the limit max size?
It turns out that size is not important. It is a default setting disabled in metamask. Something I believe should be enabled by default.
But anyway, if someone gets here, and doesn't see the image in metamask wallet, just turn on the following:
Settings > Security and Privacy > Display NFT Media