Have any of these Android “service level agreements” ever eventuated? It’s not the first time Android was supposed to get updates for more than 18 months.
Google has been reliably delivering OS and security updates for the promised timeframes on their Pixel phones. I've run a few different models out to the end of their promised support window and updates were timely for the duration.
My Galaxy A51 just got Android 13 and the corresponding security update for January and this was a mid-range Android phone first released over 3 years ago. It's supposed to get more security updates after this although no more full Android versions (not like I can really tell anyways). So yeah, there are Android phones with more than 18 months support.