Just my preference, but I wouldn't try to hide the OSB -- it's a cabin
I'd use a rag roller. First prime the OSB with a high quality primer. Then paint the base color (I usually use a lighter color) first. Then use the rag roller with paint mixed with glaze. You'll need to use a crumbled cloth to do the edges. Paint the trim (or tape well) after and it'll look great! The OSB will add additional texture and interest.