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
@feditips
Hi @feditips, Im brand new from Twitter and a little lost. Is there a Mastodon group that shares pictures/photos?
You can follow hashtags such as #photography or whatever you're interested in. Posts with those tags will appear in your feed.
There's also a group account you can follow at @photography which will share photos posted to it to all the group's members.
Also, don't want to overwhelm you, but there is an entire photo sharing social network on here called Pixelfed. It is compatible with Mastodon, you can follow Pixelfed accounts from Mastodon and vice versa.
@feditips
Awesome!! Thats what I want. Im a happy, .....wait, what do we call ourselves on Mastodon?
As a citizen of the Fediverse, fedizen is the term I would choose.
https://joinfediverse.wiki/Main_Page
https://joinfediverse.wiki/Special:MyLanguage/What_is_the_Fediverse%3F
Fedizens of the Fediverse, mastonauts of Mastodon :)