Well, the first thing about the armour is that you might forget the shield. In Frank Herbert's Dune universe, the 'energy shield' will stop everything thrown at it. That's why you need swords and blades, so that you can bypass the shield with a 'slow moving edge.'
So for the alarm you need your shield and a blade. The rest is extra.
They make a big deal of Fremen surviving in the desert and how you wouldn't last 2 hrs without a suit out there. But most of the time they go around mouth breathing through the desert despite showing us the mask part of the suit several times. It was like they decided to throw away that part of the suit in favour of face shots of the actors. Don't make something a big deal and then not use it.
You've miss understood the still suit. It is not the atmosphere that is killing them. They can breath it, it's the vaporisation, the loss of liquids that is killing them, because in the Dune world there's no surface water. It's all in aquifers and in other deep reservoirs, like what we have in Mars and Ceres today.
The still suit captures the essential juices, but you still have a problem with the number two. No workaround with that stuff, unfortunately. And you must know from Covid experience that it is difficult to speak clearly, while wearing a mask.
They could have got around that with technology, but then the sound would have been even more garbled. So essentially the writer might go through all the processes, but for the film industry they need faces and lip motions.