Just because a respiratory infection CAN cause gaping it does not mean that that IS the cause.
As I said earlier, she may be gaping to tell you to go away or she may be too warm.
What is the temperature in her cage and what is the temperature on the branch where she is basking?
Also, a chameleon who is eager to get out of an enclosure where she lives with another chameleon is telling you in the only way she can that she needs to be in her own enclosure, alone.
White deposits around the nostrils are not a cause for concern. They are typically just excess minerals and there is no reason to change anything.
It can also be that he is beginning a shed, which is something normal that all chameleons do from time to time.
The signs of pregnancy in Jackson's are color change, steadily gaining weight and acting defensive.
That does not mean that a color change and defensive behavior are absolute indications of pregnancy.
When chameleons are stressed, they change to a stress coloration.
When you use the forum search feature you can find very helpful past posts like this one which has pictures of a very far along gravid female Jackson's
https://www.chameleonforums.com/jackson-pregnant-possibly-giving-birth-soon-82086/
Chameleons are sensitive to changes and they do take time to adjust to new surroundings.
You just got these chams, so they are adjusting.
The fact that they eat and drink is very good.
Please buy, borrow or make another enclosure for her without further delay, so she can be separate from the male, so that her stress is minimal.
Constant stress in chams, just like it is for humans, can lead to illness.
Look at my avatar. That is a male Jackson's showing his stress colors.
Why? Because he did not like the camera flash.
You can post pictures by following these instructions
https://www.chameleonforums.com/how-post-photos-video-3609/
You can post clear close up pictures of your chameleons and also post pictures of their enclosure(s).
It would be best for your chams and yourself if you review all of the info on the Jackson's care page
https://www.chameleonforums.com/care/caresheets/ to ensure that all is the way they need it to be.
There is plenty of info in that area of the website, such as FAQs, enclosures, health and more
Here is a link to the FAQs in resources section, accessed from forum pages by clicking on the Resources tab near the top of the page: