Fenix/Bennu/PixTudio already supported 16 and 32bpp maps, fpgs and fnts. I guess what Drumpi is asking is if it is not possible to use Bennu's Map and Fpg formats for the 16 and 32bpp versions. That would bbe of course very interesting, because there is already a limited amount of tools that can operate these formats, but you might have other plans... In that case I hope you opt for different magic numers than bennu uses today (bennu uses "m16", "m32", "f16", "f32") so as not to complicate the live for the already existing tools.
Bennu/PixTudio formats support transparently GZip compression.