Some parts of this don't really make a lot of sense.
The OP is making it out like GrapheneOS can't do things it can, when the only reason it cannot is because they're making the choice to not let it do that for them.
They almost certainly didn't need a second device for banking, as an example.
There are many ways people choose to use GrapheneOS, of course, but if you're doing a write-up, it should be clear to readers that the arbitrary restrictions you put on yourself (such as not using sandboxed Google Play) isn't something that has to do with GrapheneOS, but rather the choice you're making.