If you split into two separate systems you'll need to downsize the main trunk(s) to allow for adequate air flow (otherwise you'll find that you're not getting enough pressure at each of the registers).

just going by what I have learned Your situation most likely is different Stop any mold of you have any    Mold doesn’t like dry, bright conditions with air flow I put out 2 US flags.  

I have my gas license with a specialty in ductwork and airflow.

One of them went well, for a couple grand we put up walls that allowed air flow and a dehumidifier and it rented fairly quickly.

By running air from the air-handler to the garage you will create a negative air flow inside the house.

Airflow was around $10k for everything, which included new electrical and gas lines, all the equipment, ducts, permits, etc.

You can easily tell due to reduced air flow from the vents and the airflow being warm.

That does have the negative that you can't close off or reduce airflow in certain areas to change the flow but that usually isn't a big dealYou have the right idea to move the WiFi into a closet.

With this item the insulation can be blown in and you wont have to worry about it blocking the air flow. 

I'd also wait a few days after their quarantine is over and make sure there is good air flow and you have a N95 mask on when you do go in.