October 2, 2020 updates:

India ("Travelers aren’t allowed to transit through Delhi")
New Zealand (Newly added: "All travelers entering New Zealand must register for their 14-day managed isolation and quarantine prior to departure through miq.govt.nz. They must also show proof of their pre-booked Managed Isolation Allocation System (MIAS) Voucher at check-in.")
Palau ("Travelers must apply for and obtain a Quarantine Certificate before departure and are subject to quarantine for 14 days.")
St. Maarten (Newly added: "Travelers arriving into St. Maarten must obtain a health declaration form from stmaartenentry.com and complete it before arrival. They must also have a medical certificate with a negative COVID-19 PCR test result issued no more than five days before arrival. This doesn’t apply to children 10 and under.")
Turks and Caicos (Newly added: see below)
Costa Rica ("All passengers entering Costa Rica must complete Costa Rica’s health pass form in English or Spanish no more than 48 hours before their departure. This will generate a QR code which must be presented upon arrival.")


Turks and Caicos:
All travelers arriving into the Turks and Caicos Islands must have a travel authorization completed at least 24 hours before departure. Passengers can apply for travel authorization at turksandcaicostourism.com and must present it to immigration upon arrival. Travelers must also have a medical certificate with proof of a negative COVID-19 PCR test result issued no more than 5 days before departure. This doesn't apply to children younger than 10 years old.

Travelers are also subject to medical screening and quarantine for 14 days upon arrival.

David