I have a K6 and it fits fine in a backpack. A bit heavy. I don’t generally travel with it but if I did I’d probably choose one of the many low profile 65% instead.
Build quality, like others have probably said, you can’t go wrong with Keychron, and they have mac keys. If you just want to get the one kb for your use case and not interact with the hobby beyond that, they’re who I’d chose from.
The problem with neoprene is that it’ll absorb dust, skin cells etc and you’ll see a color change really fast. you want to wash a mouse pad every now and then and if its glued into your desk you wont be able to do that. Water will seep through into the wood below if you try and give it any kind of decent wash too.