My FP2 turns 8 today, and it is still working well. It’s still my only Android device, but I don’t use Android much anymore.
Last year I was lucky to get a second hand Librem 5 phone for a very good price, and it turned out that’s the perfect smartphone for my use cases. It runs a Debian based OS. And since I use Debian on all my devices that’s a perfect fit. It gets all the (security and other) updates Debian gets, so I’m hoping to be able to use it for the next 10 years or even longer.
I’ll continue to use my FP2 as backup phone as long as it is working (hopefully a few more years).
Great to see other people here with an 8-year-old FP2 
Edit: Thanks for the badge, that was quick! 