Metzee runs in a web browser, and that is the whole product — on an iPhone, on Android, on a laptop. There is nothing to install for either platform today.
So the honest version of this question is not "why is iPhone behind" — nothing is ahead of it.
What you can do on an iPhone right now
Everything. Watch a show, bid, win, pay, track an order, open a return, run a store, go live.
Open the site in Safari. If you want it to feel like an app, add it to your Home Screen from the share menu — it opens full-screen and sits with your other icons. No store, no download, no update to install.
Why a browser first
It works everywhere at once. One thing to build, one thing to fix, and nobody waiting a week for a release to reach them.
Nothing to update. A fix is live when it ships. An installed app that people do not update is a support problem that never ends.
Nothing to install before you can look. A live auction is something people arrive at from a link. An install standing between the link and the show loses most of the room.
What a browser genuinely gives up
Notifications are weaker. The biggest real cost. An app can reach you reliably when a show starts or you are outbid; a browser is less dependable about it. Notifications, explained
It cannot sit on your dock by itself without the Home Screen step above.
Those are the honest trade-offs, and they are the reason apps are worth building eventually rather than never.
When there is one
You will not have to hunt for it — the site will say so. Until then, treat anything claiming to be a Metzee app as not ours. Fake Metzee websites and messages
If something does not work on your iPhone
It is far more likely to be an old Safari or a weak connection than the platform. Live video is the part that is fussy; the rest of the site is not. Which browsers work?
More: do I need the app?, what you need to watch a show, does Metzee work on a tablet?.