You don't need to use the official Mastodon apps, they're not the best way to use Mastodon. The official apps only arrived last year, and they were intended as "Fisher Price My First Mastodon" things with a restricted set of features.

Third party apps have been around longer than official ones, and include way more features. You can sign in with the same account on all apps.

On Android try Tusky, Fedilab, Megalodon, Tooot

On iPhone/iPad, try Toot!, Ice Cubes, Ivory, Mona