Of course you can. As far as I know (but if anyone knows better you can contradict) on IzzyOnDroid you don’t even have to submit, some maintener just picks the apps they think are worth it and they add them.

This is a small project with few users and not well known in the open source community so it has not been selected, considering there are already well-established Lemmy clients that do their job.

Once they have the “big ones” on IzzyOnDroid that’s more than enough for them, since having more apps implies more costs and maintenance nuisance.