> And it's necessary to have a second phone to actually use any of that while maintaining access to one's banking app.

Partially accurate / misleading at most.

I have a phone that can be unlocked, and I will lose access to my banking app (among other things I require) if I do so.

If your “partially accurate” objection is that I didn't describe a perfectly universal experience, I will be greatly disappointed.

What does “unlocked” mean, here?

Are we talking about root checks? Bootloader unlock?

Vouching your comment from dead to reply in good faith:

your bank’s app sucks, tell them they suck,

and or use the webapp.

Tens of thousands of financial institution apps work A-OK on GrapheneOS,

that is my objection.