That’s generally how all services start out, though. It sucks, but you can’t just wait for a platform to get big, you have to actually use it, you have to be the change you want to see.
A big advantage of federation too is that all platforms can interact with eachother; a user on mastodon can interact with this post on lemmy, an iceshrimp user can interact with users on bonfire; etc etc. Platforms on the fediverse have the advantage of not needing to start from scratch.
And, there is nothing stopping them from using facebook alongside friendica, i use redlib when lemmy doesn’t have a community i’m interested in, for example (although i definitely main on lemmy). we don’t have to completely stop from using a platform, both is fine :)
Friendica is compatible with mastodon’s api, so you can use the mastodon app. That’s the only way i think of on iOS :/
You can also use the website as a PWA, safari has partial PWA support