Ask HN: What are mainstream smartphones with LTS?

I'm an average user for average smartphones.

But I'm more sensitive to their security issues than before. Which is why I'm searching a phone that offers long term (software) support.

I don't want to rely on niche vendors, and do not need vendor support, community LTS is fine.

But i'd like to have around 5 years support instead of the planned obsolesence that forces me to buy a new phone every 2 years due to outdated OS.