I think that there is no restriction, but you'll have to publish this as a "non-deployable" and "paid via vendor" because you'll have an iphone app and not UPM installable add-on.
Here's an example of simular add-on https://marketplace.atlassian.com/plugins/com.obss.plugin.jiraclient
Go through the Marketplace docs for more information:
Here's some quotes:
What's the difference between deployable and non-deployable add-ons?
The Universal Plugin Manager (UPM) can install add-ons automatically into Atlassian applications. However, some items in the Atlassian Marketplace may not be suitable for automatic installation.
The Create new add-on form has a Deployable option that indicates whether an add-on installs with UPM. You should not check the Deployable option if your add-on consists of multiple JARs. The Atlassian Marketplace and UPM do not support Try, Buy, Install, Upgrade, and Renew buttons for non-deployable add-ons. Non-deployable add-ons cannot be sold under the Atlassian Marketplace Vendor Agreement as they do not support the UPM licensing API.
Additionally, if your add-on requires multiple downloads, configuration or license files on the file system, or if your add-on is not meant to be installed into the host product (like JIRA Client, for example), then do not check the Deployable option. Your add-on is still available for download, but the UPM does not attempt to install it in the host product.
Customers pay a fee to use your add-on. Customers purchase add-ons directly from you or your external website. You supply your own licensing and billing system.
I’m a designer on the Jira team. For a long time, I’ve fielded questions from other designers about how they should be using Jira Software with their design team. I’ve also heard feedback from other ...
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