There is now a dedicated Pixelfed app available on Apple's app store for the first time. It's not the official one (which is still in testflight) but a third party one called Vernissage:

https://apps.apple.com/app/vernissage-for-pixelfed/id1663543216

It's a free open source app, you can follow its official account at:

➡️ @vernissage

(If you're unfamiliar with #Pixelfed, it's the Fediverse's alternative to Instagram. Pixelfed accounts can be followed from Mastodon and vice versa, more info at https://pixelfed.org.)