Dash AC spitting out foam bits

I can't say specifically for your WH, but most of the time, that foam is from the seals (like weatherstrip) at the joints in the duct work and at vents. There is also foam seals used at the blend door in most vehicles where the cooled, heated and fresh air is mixed. Common for these foam seals to disintegrate and leak over time.

Mice maybe??

I had the exact thing happen last week on my personal car. It is nothing to worry about at all. Turn your fan on HI and just let it spew out. A help would be to set your AC to bring in outside air and use a leaf blower into the cowl vent to assist in the removal of the foam bits.

I have had my dash apart and there are no foam ducts used on the WH chassis. On mine the air intake is down on the firewall right in front of the passenger seat. Is there any chance that bits of foam could be ingested at this location? There is no filter.