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There is this on online MRAID emulator, here: [link]
Also has a free iOS app here: [link]
And for Android here: [link]
All the above require you to paste the embed code from the adserver, I don't think you can just use the raw creative files. It is open source, so depending on your resources you could probably set it up to run locally without having to load the files to an adserver (caveat emptor).
Depending on your adserver/DSP there might be a companion app you can install on a mobile to test with.
If you need to see it on the actual app your serving on you may be able to target your ip or AAID/IDFA with unlimited capping and volume to essentially force it to appear.