Flagships is the key word here, everything below is hit or miss.Your Pixel 3 got it's last update a few months ago... and it only got 3 years of OS and security updates, but you don't seem too angry at Google? I'm currently still using my Pixel 3XL and enjoying it... losing updates isn't the end of the world, updates aren't magic armor. What protects you the most is being smart about how you use your phone. In fact monthly security updates quite often don't have anything security related in them... just bug fixes.
And I also wanted to see longer software support... and in fact, because customers complained, Samsung and Google have both extended their support considerably, Samsungs now offering 4 years OS and 5 years security updates, and Google's giving 3 years OS and 5 years security updates. That's longer than most folks will keep a phone
I'm not a huge fan of Samsung... but they do support their flagship phones very well anymore.... better than anyone else besides Apple.