A useful list of which countries are welcoming foreign visitors and which still have restrictions.
Some countries require completion of a passenger information form, most require proof of vaccination and some request proof of travel insurance including COVID cover. The FCDO website (www.gov.uk/foreign-travel-advice) has a clear summary of country entry requirements in more detail.
Fully open, no significant restrictions*
Argentina, Belize, Bolivia, Brazil, Colombia, Costa Rica, Cuba, Ecuador/Galapagos, El Salvador, Guatemala, Guyana, Honduras, Nicaragua, Mexico, Panama, Paraguay, Peru, Uruguay, Falkland Islands
*for fully vaccinated travellers
Open, but with some restrictions
Chile (Easter Island opening 1 August 2022 but with 4 days mandatory quarantine) - arrival testing performed at random, Venezuela - arrival test required