For what its worth, arrived in Sao Paulo this morning and customs/immigration was just like a typical (any country except Canada or China) pre-pandemic customs/immigration visit. Walked straight up to the "Foreigners" booth with a very bored looking official who took my passport asked tourist or business, number of days, stamped my passport and wished me good day.
So insurance definitely isn't something they care about at the moment (but I still consider my Geoblue policy at ~$70 for a 10 day stay a wise investment)
Lincoln