Motorola G6 Plus (and many other Android phones) is supported by LineageOS which is up-to-date version with security updates.
I use LineageOS and it is true that I have to use Magisk to have banking app working. And I understand that this is not for everyone.
I just wanted to mention that there is a way to use older phone and have security updates longer than vendor provides it. And even longer than Apple.
I get the argument about binary blob updates. Security is never 100%. And it also shows another reason why binary blobs make things worse.