I think for default blue is good enough, there's a reason it's default for so many apps but I do think optionality is king.

Being able to choose the accent color would be great, displaying a few pre defined options and an option to fine-pick, like in Nostrudel for example (but with better picked colors, including our lovely nostr purple, not just simple primary colors) replacing the color in the elements I circled.

But I do like the focus on neutral contrast colors for most of the app, the app design looks impeccable so far!