Thinking about how the Ultimate Hope title is just that, a title.
Like, Makoto only got his title because he defeated Junko. That's it. He defeated Ultimate Despair so he became Ultimate Hope (even tho Kyoko should have that title too because he couldn't have done it without her, we literally have a whole ass separate ending to prove that).
But unlike Junko, and honestly the rest of Ult Despair, he doesn't chase after hope. He just wants an average ass life (boooooooring).
And same goes for Hajime/Izuru. He only has the Ult. title because he has every talent in him. He's Hope's Peaks' hope, so that makes him the Ultimate Hope. (Goes the other way too, once he became their despair, he became Ultimate Despair.)
And nagito doesn't really count bc no one considers him ult hope, except himself that one trial, but if you want to, he gave himself the title when he tried to end the remnants of Ult. Despair, making him an Ult. Hope in a sense.
What I'm getting at here is that the Ult Hope title is very flexible, similar to the Ult. Despair. It can belong to multiple people for different reasons.
So, wouldn't that mean Ryoko could be an Ultimate Hope?
She is literally Junko without her obsession and need for despair. She is Junko's base. Junko came from a version of Ryoko that gave up and embraced despair because it made her feel something. Ryoko is what makes Junko feel despair because Ryoko cares when Junko doesn't. Junko, in a backwards way, HOPES for Ryoko's existence, because then she can experience despair. Without her, Junko could not be Ult despair.
Junko is Ryoko's Ultimate Despair and Ryoko is Junko's Ultimate Hope.