Now I know what you're saying, mods are not possible on iOS, and Jundroo will most likely not support it too(unless they decided to rename mods to plugins to bypass Apple's policies)

Main topic:
You know how you can access most of the files on your iOS device via the Files app in On my iPhone/Ipad, and the contents of it would be similar to the ones on the AppData/LocalLow/Application Support's Jundroo/SimplePlanes folder

There should be a file inside of the SimplePlanes folder on iOS named settings.xml, and inside the xml file should have a <EnabledMods /> section where, obviously, the mods you enabled are there.

And with that information, if you manage to get the mods' root filepath and the other info with it, you should be able to use mods(after editing settings.xml)

The problem is that you have to find a way to tweak the SimplePlanes app(Jailbreaking your iOS device could possibly allow that but the method to do this is unknown at the moment and there is no reputable and stable Jailbreak above iOS 16 at the moment) to allow file detection inside of a mods folder that you have to create yourself, and the root filepath for the mod, or whatever iOS SP takes for the path variable inside of the settings.xml file

I don't actually know how to end this forum post so bye