I think what’s happened is that unlike windows each manufacturer is given the source code to make their own unique version of Android that’s incompatible with anything else typically. So once the lifetime of the product has expired as intended that development ceases.

Google has tried to resolve this problem with their android security updates. But this isn’t a perfect solution either.

The manufacturer argues that it’s not profitable to maintain legacy devices as you’re incentivizing the customer to not buy the next model. So as consumers we are asking manufacturers to impact their own profits and capitalistic goals. This is unfortunately hopeless without a regulatory power to force that consumer interest.