Lots of threads on refunds from airlines, I have not seen one yet specific to Airbnb, and wanted to share my own experience in the past few days.
Short version: After passing on their initial offer to only refund most of what I had paid in advance for an upcoming stay, after a little prodding, Airbnb eventually acceded to my request for a full cash refund.
More details: I'm not a big user of Airbnb. Not a big fan, either; we prefer to book directly or via booking.com for a variety of reasons well articulated previously by others. Still, when there are no other reasonable options, we will look at Airbnb. That's what we did for a planned family visit to Yosemite National Park in May. With 5 family members coming from overseas, we had a house (kinda sorta) "in" the park booked through Airbnb. Of course, that trip is now off (all of our family members are on the other side of the world and couldn't get here even if they wanted to; our flights to there are canceled, and in fact the park is closed). So none of that is happening.
I received an email yesterday from Airbnb informing me that I was entitled to a full refund if my travel plans had been impacted by the COVID19 pandemic. I went online and followed their instructions to request my full refund. Their app informed me that my full refund would consist of about 80% of what I already paid being refunded back to my credit card, and the remaining 20% would be in the form of a credit to be used on a future trip - in other words, a voucher. There was no expiration date specified. That didn't sound to me like a "full refund". I called, and after holding about 20 minutes, explained our situation, was told to expect a follow-up message from their "extenuating circumstances" team. A few minutes later I received their message. Messages bounced back and forth, again with them offering about an 80% cash refund. I pressed for a full refund (since that's the term they were using). They asked me to document, or simply "affirm" that our trip was impacted by the COVID pandemic. I did. Minutes later they sent a message saying they would refund 100% of what I paid, back to my credit card (not a partial voucher). I thanked them.
So, bottom line: at least in my experience, Airbnb "did the right thing" (IMHO) and did provide a full refund. It did require a little prodding but they were reasonably easy to work with and it left me feeling satisfied.
If you have to cancel an Airbnb reservation, expect them to want to provide a refund in the form of cash plus a partial voucher, but if you push back on that and ask for a full refund, it seems they will (at least in some cases) do that.
Hope that helps someone. Good luck.