We just got back from Venice. N95 was required (provided if needed) to enter San Mark's Basilica, Campanile Tower.
Surgical masks was used at all other locations, ie.. all flights (TAP Air), coop, indoor locations, shops, restaurants, vaporetto...
Outdoors, hardly anyone was wearing any mask...
As for testing, we went to one of the pharmacies on this document. Made appointment on our first day there, 22€ per person, paid when appointment scheduled.
https://www.univiu.org/about-viu/brochures-reports-and-regulations/covid-19-protocol-and-practice/covid-test
Results on-site in 10 minutes, email in 30 minutes..
On the return flight to U.S. from Portugal (17 hour layover) everyone needed to fill out a Covid test document. Lots of copies of the form available before entering gate area.
Once completed, airplane personnel checks, passport, cdc card, boarding pass, covid test.
BTW, althought we had filled out the both Portugal and Italy dPLF, it was checked only at gate before departure from Miami to Portugal. No one asked on connecting flight to Italy and return flights to the U.S.