Thor could also be in the mix. His god - like powers and different cultural background compared to Yelena would create an interesting dynamic. Maybe Yelena is initially in awe of his abilities or she challenges him in some way, leading to an engaging interaction.
One possible plotline could be Yelena initially being distrustful of the Avengers. Maybe she has been taught to view them as enemies, but as she gets to know them, she realizes they have similar goals. For example, she might find common ground with Natasha's former teammates in their fight against evil.
Well, they might have a deep conversation about their different views on the world. Eren could try to convince Zeke of his more radical approach to saving the Eldians, while Zeke might push back with his own ideas of euthanasia for the Eldians. It could be a very tense encounter.
They could start to plan a strategy to deal with the Marleyans together. Since both have their own experiences with Marley, they might come up with a complex plan involving Titan powers and political manipulation. For example, using Zeke's position as a Marleyan weapon and Eren's influence within Paradis.