I'm the developer of Summit. Unfortunately I don't see anyone mention Summit but I would suggest giving it a try as well.
I think I've been a bit slower to implement certain features compared to the other apps, but the app is heavily focused on scalability and performance. Give it a try just in case you might like it. Play store link: Summit for Lemmy
Is that something you would be open to working towards? Since the growth of Lemmy is attributed to Reddit becoming "closed", I think many users might see it as a dealbreaker or be less inclined to use a closed-source app.
My feelings towards this might change in the future. However for the time being, my enjoyment of the project hinges on the project being closed source. Ie. open sourcing the project will likely lead to me stepping away from the project. So even if this significantly impacts the number of users, I would still prefer to keep it closed source. I'd rather have a fun side project I made than to create a popular project that I do not contribute to. It is unfortunate but it is what it is.