How is it usable if it is insecure? People bank on these things.
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.
It may even receive system web browser updates, as those tend to go on for much longer than OS updates with Android.
With a little care, it is likely to be fine.