Neoprene is definitely more comfortable than latex too. Contrary to intuition, the neck seals don't have to be made of smooth rubber to keep water out. The neck dams for certain popular diving helmets are made of 2-mm neoprene with nylon on both sides and they have worked really well for many years. A small amount of moisture seeps past the knit nylon over time but the amount is so small that it doesn't degrade comfort or safety. The only situation you'd have to be concerned about might possibly be floating in your drysuit for an extended period in cold water with no assistance. But even then a Kokotat paddling drysuit isn't really the kind of protection that's needed.

You can buy pieces of 2-mm neoprene of whatever size you want at Seattle Fabrics. If you want stretchier material with one side bare then you can try to find a shop that stocks Rubatex. This has been the preferred neck seal material for diving drysuits for a long time but that may have changed during the last few years. Diving suit materials have become much more exotic recently.