I can see that for the online version it maybe be a bit more polemic if the site keeps the imported archive in localStorage (OTOH it is offline local storage so maybe it would be fine as well) but for the Webxdc version it is much clear that this would be useful and has no security questions since the webxdc is completely offline sandboxed version of the website, saved in the user's device

It makes it a bit hard to use for me if I have to select the file to import every time, what is worse, I would prefer to keep the file safe inside the webxdc (and hence the Delta Chat app private internal storage) currently I have to keep the file exposed in the Downloads folder on Android to select it and import it every time I want to use MARL